Management of primary congenital glaucoma in the Indian population

Abstract

Primary congenital glaucoma (PCG) is a leading cause of childhood visual impairment and blindness worldwide, with a disproportionately high burden in low- and middle-income countries such as India. Early diagnosis and prompt surgical intervention are critical to prevent irreversible vision loss in affected children. This study aimed to review and synthesize current evidence on surgical management strategies for PCG in the Indian context. The objective was to identify the most effective, evidence-based surgical approaches to optimize outcomes in Indian children with PCG. A comprehensive narrative review was conducted, followed by a systematic literature search of PubMed, Google Scholar, and Scopus databases for the surgical management strategies in Indian context for PCG eyes. Keywords included “Primary congenital glaucoma,” “trabeculotomy,” “trabeculectomy,” “goniotomy,” “glaucoma drainage devices,” “complications,” and “India.” Only English language articles with full text availability were included. Data were extracted and analyzed to compare surgical outcomes and determine best practices. Trabeculotomy and goniotomy remain first-line surgical interventions, with combined trabeculotomy–trabeculectomy showing superior long-term success rates in the Indian population. Glaucoma drainage devices are primarily reserved for refractory or advanced cases. Lifelong monitoring is essential due to the potential decline in surgical success over time. In the Indian setting, combined trabeculotomy–trabeculectomy represents an effective, evidence-based surgical strategy for PCG management. Early surgical intervention and individualized treatment remain critical to preserving vision and reducing blindness in affected children.

Primary congenital glaucoma (PCG) accounts for 4.2% of all cases of pediatric blindness in India.[1] Early identification of the underlying phenotype, timely diagnosis, and prompt intervention are critical to prevent irreversible vision loss as an earlier age of onset is associated with more aggressive disease and poorer visual outcomes.[2] This fact is particularly relevant to our population since the average age of presentation in India is lower than in Western countries.[3]

A systematic review was conducted to evaluate the spectrum of management strategies and their clinical outcomes in Indian children diagnosed with primary congenital glaucoma to identify and synthesize the most effective and evidence-based approach to treatment in this population.

Methods

This hybrid systematic-narrative review followed PRISMA 2020 guidelines for transparent reporting.

Eligibility criteria

Inclusion prioritized studies reporting original data on PCG diagnosis, clinical features, or management outcomes in Indian patients. Eligible designs (in descending order): randomized controlled trials, cohort/case-control studies, case series (≥5 patients), and unique case reports. Exclusions comprised reviews, editorials, commentaries, and secondary glaucoma studies. Only English-language full-text articles were considered.

Information sources and search strategy

PubMed, Scopus, and Google Scholar were searched up to April 30, 2025. Terms included “Primary Congenital Glaucoma,” “Infantile Glaucoma,” “Diagnosis,” “Management,” “India,” and relevant MeSH, combined with Boolean operators (AND/OR).

Study selection

Records underwent deduplication, followed by independent title/abstract screening by two reviewers. Eligible full texts were then reviewed for inclusion, with disagreements resolved by consensus.

Data extraction and synthesis

Data were extracted via standardized templates capturing study characteristics, demographics, diagnostics, presentation, interventions, outcomes, and follow-up. Due to heterogeneity, narrative synthesis was performed. Supplementary literature supported nonoutcomes sections.

Results

The selection process is reported as per PRISMA guidelines in Fig. 1. The initial screening shortlisted 91 abstracts. Further review excluded 22 studies due to not being relevant to PCG, and 28 studies included populations other than the Indian population, which has been presented in context to the western literature. A total of 41 studies were included to synthesize the following information.

Figure 1.

Results of the study selection process, as per PRISMA guidelines

Discussion

PCG is an isolated, nonsyndromic congenital ocular disorder characterized by impaired aqueous outflow, resulting from abnormally developed trabecular meshwork (TM) and anterior chamber angle.[4] Based on disease onset, it is classified as neonatal (<1 month), infantile (1 month to 2 years), or late-onset/juvenile PCG (older than 2 years). The severity of PCG can be objectively staged based on the age of onset, corneal diameters, axial length (AL), corneal haze, and number of surgeries required[5] [Table 1].

Table 1.

Severity staging for primary congenital glaucoma (Gupta V et al.)[5] Each parameter is worth 1 point. A case is severe if the total score is ≥4

Parameter	Severe	Nonsevere
Onset age	Neonatal	Infantile
Corneal diameter at presentation	≥13 mm	<13 mm
Presenting AL	≥24 mm	<24 mm
Presenting corneal haze	Total corneal haze	Anterior segment details visible
Persistence of corneal haze after IOP-lowering surgery	Yes	No
Number of Surgeries required for IOP control	>2	≤2

AL – Axial Length; IOP – intraocular pressure

Etiopathogenesis

Up to 40% of PCG is inherited in an autosomal recessive pattern with variable penetrance, while the majority occur sporadically.[6] In addition to increasing the risk of PCG in the offsprings, parental consanguinity is also associated with a more aggressive manifestation of the disease, commonly found in Muslim Indian families.[5,7] Several genes have been identified to be associated with this morbidity. Genetic studies of affected families have identified four loci linked to PCG: GLC3A on chromosome 2p21, GLC3B on chromosome 1p36, GLC3C, and GLC3D, situated on 14q24 in close proximity but not overlapping each other.[6] Mutations in Cytochrome P450 1B1 (CYP1B1) are the most frequently recognized genetic abnormalities in PCG.[8] Additionally, latent transforming growth factor beta binding protein 2 (LTBP2) gene and tunica interna endothelial cell kinase (TEK) gene mutations have also been linked with PCG.[9,10] Gupta et al.[11] also identified missense mutation (c.1925A>G, p.Tyr642Cys) in the PLOD2 gene in a monozygotic twin pair with PCG.

Genetic mutations not only are associated with an increased risk of PCG but also can determine the severity of the disease. To determine the same, a study involving 146 Indian PCG patients aimed to correlate the patients’ genotypes with severity of the disease. The authors screened for six different mutations (Ins376 A, P193 L, E229K, R390C, G61E, and R368H) in CYP1B1 gene. Consequently, a severity index was developed. This index included intraocular pressure (IOP), corneal diameter, corneal clarity, cup-to-disc ratio, and the most recent visual acuity (VA). The most severe identified phenotype was found to be associated with a frameshift mutation (Ins376A) in CYP1B1, followed by homozygous R390C mutation.[12] In a North Indian PCG cohort, Kaushik et al.[13] compared neonatal and infantile-onset disease and showed that pathogenic CYP1B1 variants, particularly c.1169G>A (p.R390H), were greater in neonatal-onset cases (42.8%) as compared to infantile-onset cases (17.2%) and were associated with more severe presentation, greater surgical burden, and poorer outcomes. In contrast, the common MYOC variant c.227G>A (p.R76K) appeared benign.

While the precise pathogenic mechanisms of PCG are unclear, various theories have attempted to explain the same. In 1948, Otto Barkan reported a cellophane-like persistent embryonic tissue, or “membrane,” which covered the angle, attributing this membrane to be the cause of impaired aqueous outflow.[14,15,16] Worst backed this finding, eventually terming this pre-trabecular meshwork membrane as Barkan’s membrane.[17] Although this theory explained the efficacy of performing goniotomy to lower IOP in PCG eyes, the presence of Barkan membrane could not be demonstrated in histological and electron microscopic studies.[16,18] According to Anderson, angle dysgenesis and subsequent trabecular outflow obstruction were caused by developmental arrest in the uvea’s normal migration during gestation, leading to high anterior uveal insertion into the TM and anterior insertion of iris root and ciliary body.[18] In his electron microscopic study, McMenamin hypothesized that excess proteoglycans on the inner surface of TM, along with a significant increase in extracellular matrix volume, were the main pathogenic mechanisms in congenital glaucoma.[16] However, neither Anderson nor McMenamin could identify the membrane proposed by Barkan.

Nevertheless, over the past two decades, in vivo investigations of angle anatomy have been made possible due to modern advancements in ocular imaging. In an analysis of angle structures using spectral domain anterior segment OCT (SD-ASOCT), a hyper-reflective membrane covered the TM in 100% of PCG eyes,[19] similar to what Barkan described. Shi et al.[20] also isolated an abnormal tissue membrane on high-frequency ultrasound biomicroscopy (UBM) in 27.5% of PCG eyes. In addition to the Barkan membrane, maldevelopment of the Schlemm’s Canal (SC) has also been postulated as one of the underlying histological changes leading to PCG.[21,22] Researchers have identified SC in 62%–73% of PCG eyes as compared to 100% of normal eyes in their in vivo angle studies.[20,21] Additionally, decreased aqueous humor outflow (AHO) pathway arborization in eyes with childhood glaucoma on aqueous angiography confirms the functional effect of the pathological changes described so far.[23]

Therefore, it is safe to say that PCG is a manifestation of a spectrum of congenital anterior segment maldevelopment that impairs the normal aqueous outflow in genetically predisposed individuals.

Clinical presentation and diagnostic work-up

Bilaterality is seen in 70% of cases; however, the presentation may be asymmetrical.[24] In over 75% of the affected individuals, PCG manifests in the first year of life, often between 3 and 6 months of age. Globally, males are more commonly affected than females. However, a recent publication by the Indian Childhood Glaucoma Study (ICGS) group found a female predominance, with 62% of the 1155 children being girls.[3]

The classical triad of PCG includes epiphora (excessive tearing), photophobia (light sensitivity), and blepharospasm (eyelid squeezing). Parents may also notice an increased size of eyeballs or an asymmetry of the sizes between the two eyeballs which may or may not be associated with corneal clouding.

Initial clinical evaluation can be done bedside; however, since these children are often very young and likely photophobic at presentation, examination under anesthesia (EUA) is almost always warranted for better characterization of signs before surgery. During EUA, documentation of baseline characteristics, especially corneal diameter, corneal clarity, AL, fundoscopy, intraocular pressure, gonioscopy, and UBM if required in cases with corneal opacity, is essential to make a correct diagnosis.[25,26] Recent studies have demonstrated that AS-OCT may be utilized to diagnose childhood glaucoma without the need for EUA in selected cases. In a prospective cohort of infants under 2 years, swept-source AS-OCT with a “flying baby” technique quantitatively assessed anterior chamber angles and TM visibility, showing that clear TM visualization was present in all nonglaucomatous eyes but in only about one-quarter of glaucomatous eyes, thereby helping distinguish early-onset childhood glaucoma from other causes of cloudy cornea.[27] However, these promising findings are limited by the relatively small, single-center sample and may not be directly generalizable across all pediatric populations or devices yet.

For tonometry, appropriate tonometers, such as Goldmann applanation tonometer (GAT), Perkin’s tonometer, or rebound tonometry, must be employed to measure IOP at baseline to help the clinician decide the best-suited intervention depending on the target IOP.[28] In a study from India, Sihota et al.[29] determined the mean IOP in the normal pediatric population to be 12.02 ± 3.74 mmHg. IOP ≤19 mmHg on two separate occasions is considered normal in children.[30] However, it is prudent to be aware that IOP can decrease up to 25–32% with the use of anesthetic agents such as desflurane and sevoflurane.[31] Conversely, IOP may also be falsely elevated up to 4 mmHg using an eye speculum for examination. Therefore, these factors must be considered during evaluation. Once IOP has been controlled, proper vision assessment and age-appropriate rehabilitation must be performed.

Anterior segment examination typically reveals edematous cornea with Haab striae. Haab striae are horizontal breaks in the pre-Descemet’s layer (PDL) and Descemet membrane (DM).[32] These breaks must be differentiated from vertical breaks in the DM resulting from forceps-related birth injury or DM breaks resulting from corneal hydrops in keratoconus. Other corneal findings include stretched limbus and enlarged corneal diameters. A corneal diameter ≥11 mm in a newborn, >12 mm in a child younger than 1 year of age, and >13 mm in any age is considered abnormal.[33] Refraction often reveals myopic refractive error with irregular astigmatism. However, the final prescription should be dispensed only after IOP lowering at first EUA, often 4–6 weeks after the first surgery. AL is also elongated, as seen on A-scan ultrasonography. These enlarged corneas and elongated globes are responsible for the characteristic buphthalmos or “ox-eyed” appearance of a child with PCG. However, as it is caused by the sclera’s extensibility and stretchability during early childhood, buphthalmos may be present in other pediatric glaucomas as well.

Gonioscopy is an indispensable tool to differentiate PCG from other causes of pediatric glaucoma. The gonioscopy approach in children is illustrated in Fig. 2.

Figure 2.

Approach to gonioscopy in pediatric patients

On gonioscopy, the clinician characteristically finds an open angle with high iris root insertion (at or anterior to scleral spur), indistinct ciliary body band due to altered translucency of the angle, and concave iris. Such isolated trabeculodysgenesis, with no other abnormal features in the eye apart from the angle, is a hallmark of PCG.[17] Other findings include a “featureless” angle and multiple filiform iris processes. In spite of the fact that angle is an avascular structure in anatomically normal eyes, in PCG, vascular loops from the major arterial arcade may be observed above the iris root. This is known as the ‘Lochness Monster phenomenon.’ Similarly, Lister’s morning mist’ refers to the scalloped border of iris pigment epithelium and trabecular meshwork appearing through translucent peripheral iris stroma, as if viewed through the morning mist. For posterior segment evaluation, either direct or indirect ophthalmoscopy or fundus camera photography may be performed. In children, especially infants, small cups can be abnormal, and CDR must always be interpreted in the context of corneal diameter, intraocular pressure, and axial length. Based on available normative data, a vertical CDR approaching or exceeding 0.3, or marked asymmetry between the two eyes, should be considered suspicious and warrants careful evaluation for congenital glaucoma.

The same parameters should be monitored during follow-up to detect early disease progression. Though cupping can be reversed with timely and appropriate lowering of IOP,[34] progressive change in corneal diameter and AL can serve as essential tools in monitoring the disease progression.

Some other pediatric ocular pathologies may mimic PCG and must be differentiated for appropriate management. Common differential diagnoses of PCG are summarized in Table 2.

Table 2.

Common differential diagnoses of primary congenital glaucoma

Differential Diagnosis	Common Feature(s)	Differentiating Feature(s)
Megalocornea	• Enlarged Corneal Diameters	• X-linked recessive • No corneal edema or DM breaks • IOP and AL are within normal limits
Congenital Hereditary Endothelial Dystrophy	• Autosomal Recessive inheritance • Bilateral corneal clouding	• No epiphora or photophobia • Normal corneal diameters • IOP and AL within normal limits
Sclerocornea	• Corneal clouding • Partial sclerocornea may mimic stretched limbus of PCG	• Microcornea or normal corneal diameters • Often associated with microphthalmos
Birth trauma	• Break(s) in Descemet membrane	• History of forceps-assisted vaginal birth • Orientation of break is oblique or vertical, unlike Haab striae in PCG which are horizontal.
Infections and inflammation (e.g., Keratitis, uveitis, endophthalmitis)	• Epiphora and blepharospasm, child often photophobic	• Anterior segment examination will reveal corneal infiltrates, epithelial defect, hypopyon and anterior chamber cells. • If vitreous cavity is involved, B-scan may reveal mid-moderate amplitude spikes.
Intraocular Tumors	• Enlargement of globe, buphthalmic eye	• May be associated with proptosis or globe dystopia • Tumor mass can be picked up on ocular imaging

AL: Axial Length; IOP: Intraocular Pressure; PCG: Primary Congenital Glaucoma

Management

Medical management

Topical antiglaucoma medications (AGMs) are the first line of treatment for most adult and certain pediatric glaucoma. However, topical AGMs are largely ineffective for untreated PCG due to the underlying angle dysgenesis and aqueous outflow resistance.[35] Moreover, the high rate of nonresponders, limited long-term safety data, and practical challenges such as administering eye drops to uncooperative children further restrict their use.[36]

Long-term reliance on medications makes children particularly susceptible to systemic adverse effects. This is due to their lower plasma volume leading to higher systemic concentrations of topical drugs compared to adults.[37] Measures such as punctal occlusion after instilling drops and removing excess medication must be encouraged while prescribing the lowest effective concentration and minimal dosing frequency to achieve adequate IOP control and minimize systemic risks.

Specifically, caution is warranted while prescribing certain AGMs. Brimonidine, an α2-selective agonist, is contraindicated in children (<6 years/<15 kg weight) due to its high lipophilicity, which enables the drug to cross the blood–brain barrier, subsequently causing central nervous system toxicity. This commonly manifests as apnea or sedation in children. Carbonic anhydrase inhibitors (CAIs) can cause metabolic acidosis and growth retardation in children, while beta-blockers can exacerbate bronchospasm in children with asthma.

Similar to adults, local side effects of topical medications can manifest in children as well. Upper eyelid ptosis, high upper eyelid crease, superior sulcus hollowing, eyelash hypertrichosis, and trichomegaly – collectively known as Prostaglandin-associated Periorbitopathy (PAP) – can occur in children who are on long-term topical prostaglandin analogs and hence should be avoided in unilateral glaucoma for apparent cosmetic reasons.[38] They should also be avoided in secondary uveitic glaucoma for fear of precipitating recurrent episodes or cystoid macular edema.

Up to 56% of untreated children develop honeycomb epitheliopathy 2 weeks after being on topical Netarsudil 0.02%, especially if they are younger or have pre-existing corneal edema from high IOP.[39] Other local side effects include stinging and burning sensation, superficial punctate keratitis, and dry eyes with beta-blockers and CAIs. CAIs may also cause transient myopic shift and can worsen corneal edema. Clinicians must vigilantly monitor for these signs as children may not report the side effects.

Despite their limitations, AGMs have a supportive role in PCG management. They can enhance corneal clarity before surgery, provide temporary IOP control while awaiting surgical intervention, and also complement surgical outcomes by optimizing postoperative IOP reduction. The medications continue to work both after filtering surgery and after the angle surgery, even if performed circumferentially.[40]

Surgical management

Surgical management is the mainstay to control IOP in children with PCG. However, in comparison to adults, glaucoma surgery in children with PCG is particularly challenging due to their altered anterior segment anatomy, more intense postoperative inflammation, and a higher risk of failure. Moreover, the response to glaucoma surgical treatment differs in different cohorts, which depends on various factors like race, ethnicity, socioeconomic determinants, and access to health care.[41]

In India, traditionally a CTT has been performed as first-line therapy in moderate-severe PCGs due to less-than-optimal response from stand-alone angle surgeries (i.e., goniotomy and trabeculotomy).[42] However, with the advent of several low-cost circumferential angle treatment alternatives, protocols are rapidly evolving. It was first shown by Temkar S et al.[43] in India that illuminated microcatheter-assisted circumferential angle treatment gives equivalent outcomes to CTT. Subsequently, it was found superior to conventional trabeculotomy.[44] These studies demonstrated that even in the presence of severe congenital glaucoma, thought to widely exist in India,[3] a circumferential trabeculotomy holds merit. However, the procedure did not become rampant for management of disease due to the factors such as commercial unavailability of microcatheter in India as well as the exorbitant costs involved in procuring the device from outset. In this section, we discuss the various surgical modalities available for the management of PCG.

Ab interno angle surgeries

Ab interno angle surgeries are preferred in mild-moderate cases, in children aged <2 years, clear cornea, and a clearly visible angle with minimal structural distortion. Goniotomy allows aqueous to bypass the TM and exit through the Schlemm’s canal and the collector channels. It is well established now that timely ab interno trabeculotomy helps recruit collapsed aqueous channels, seen using in vivo aqueous angiography.[45] Barkan first described the technique and outcomes of goniotomy to lower IOP in eyes with PCG with a blade,[14] with reported success rates of approximately 80% over 17 years. However, proper case selection is essential for favorable outcomes after goniotomy. In another study from India, goniotomy alone had a success rate of 87.5% with one goniotomy in infantile PCG, whereas it was 55.6% in late-onset PCG.[46] As per the current evidence, excisional gonio-procedures (such as Kahook dual blade ab interno trabeculotomy and BANG) do not appear to have an added superiority over conventional MVR goniotomy in PCG.[47,48] Moreover, excisional procedures may be associated with more postoperative inflammation, thus potentially bearing a higher risk of failure.[49]

Gonioscopy-assisted transluminal trabeculotomy (GATT) is an ab interno angle surgery that involves circumferential cannulation of the SC using a microcatheter or suture under gonioscopic visualization. The cannulated guide is subsequently pulled out to deroof the TM and internal wall of SC. Grover et al.[50] described GATT using a flexible illuminated microcatheter (iTrack, Ellex, Menlo Park, California, USA). Although the outcomes are promising, this procedure is limited by the high cost of the disposable microcatheter, especially in developing countries like India, as well as unavailability of the patented devices.

Further in 2016, Grover et al.[51] introduced the use of a round-tipped 4-0 nylon suture, modified by a thermal cautery, to similarly cannulate and deroof the SC. Due to its equivalent efficacy, safety, and significantly lower cost, suture-GATT is now the preferred procedure among most surgeons, especially in areas with limited availability of microcatheter. Circumferential suture-GATT was found to be superior over hemi-GATT in mild-moderate PCG eyes, in a prospective RCT using 6/0 round-tipped prolene.[40] In this RCT, the authors found a significant reversal of average CDR, corneal diameter, and AL in the circumferential-GATT group. However, this was not significant in the hemi-GATT group. Due to the comparable efficacy along with cost-effectiveness and convenient availability of the resources required to perform the procedure, circumferential suture-GATT is slowly taking over as the first line of therapy for PCG in India.[52] However, the long learning curve for GATT, particularly in PCG eyes, is a significant limitation of its widespread utility.

Accurate cannulation of the SC is essential for the surgical success of GATT. To achieve this, the visualization of angle anatomy can be enhanced using various maneuvers. Intraoperative compression of the ipsilateral external jugular vein causes pooling of blood in the Schlemm canal, thus improving its visualization prior to cannulation.[53] Alternatively, intracameral indocyanine green dye (0.2%) or trypan blue injection causes band-like staining of both the anterior and posterior TM; thus, angle structures could be identified even in eyes with hazy cornea.[54,55] Inverted Ångström sign on intraoperative OCT (iOCT) has also been described to identify correct cannulation of the SC by the suture during GATT.[56] Occasionally, the surgeon may be unable to identify or cannulate the SC, despite being assisted by the above maneuvers. In such cases, limited-extent gonio-surgeries, incisional (goniotomy) or excisional (trabectome goniectomy, Kahook dual blade goniectomy or bent needle ab interno goniectomy), can be performed [Table 3].

Table 3.

Differences between the ab interno and ab externo angle surgeries in eyes with primary congenital glaucoma

	Ab interno	Ab externo
Surgical Approach	Angle structures approached from the anterior chamber via clear corneal incisions	Angle structures approached externally via conjunctival and scleral dissection
Prerequisites	Clear cornea and adequate visualization of the angle	Can be performed in hazy corneas when angle cannot be visualized
Indication	Mild-moderate glaucoma	Severe and advanced cases
Visualization of surgical field	Requires a gonioscope or endoscope for visualization of structures	Direct visualization of angle structures via conjunctival and scleral dissection
Postoperative course	Faster recovery and lesser postoperative inflammation because of minimal tissue disruption	Longer recovery, more postoperative inflammation, greater scarring and fibrosis of tissues due to greater surgical manipulation
Repeat surgeries	Spares conjunctiva for future filtration surgeries	Resultant conjunctival and scleral scarring may pose limitations for future filtration surgeries
Examples	•    Incisional Goniotomy •    Circumferential ab interno trabeculotomy (GATT) •    Excisional goniosurgeries (Trabectome, Kahook dual blade, BANG)	•    Trabeculotomy (Harm’s trabeculotome) •    Suture-assisted circumferential trabeculotomy •    Illuminated microcatheter-assisted trabeculotomy

Although GATT is associated with minimal surgical manipulations, complications such hyphema, iridodialysis, cyclodialysis, cannulation in the suprachoroidal space and rarely corneal edema, Descemet membrane detachment, accidental injury to lens, and cystoid macular edema have been reported.[57] Some authors have demonstrated similar efficacy with Trab360^TM (Sight Sciences, Menlo Park, CA, USA), reporting a success rate of up to 80%.[58] This device performs a 360^o ab interno trabeculotomy using a retractable suture microcatheter with a bent cannula and viscoelastic reservoir for single-port viscocanaloplasty and trabeculotomy. However, evidence on its efficacy in the Indian subset of patients is lacking due to nonavailability of the device.

Ab externo angle surgery (Trabeculotomy)

In older children and those with more advanced disease, hazy corneas, and buphthalmic eyes, ab externo trabeculotomy—with or without combined trabeculectomy (CTT)—can be performed. Ab externo trabeculotomy involves the identification of the Schlemm’s canal externally after conjunctival and scleral dissection and cannulating it using a surgical instrument (trabeculotome), microcatheter, or prolene suture. The roof of the Schlemm’s canal is subsequently stripped to create a path for aqueous outflow. In a network meta-analysis of RCTs, Lee et al. found that illuminated microcatheter-assisted circumferential (360°) trabeculotomy was more efficacious than conventional partial trabeculotomy (typically using Harm’s trabeculotome over incisional area of 120°)[59] with respect to IOP control and surgical success.[60] Trabeculotomy alone performed at ≤6 months of age is associated with better outcomes than the same intervention done after 6 months of age.[61] However, a single procedure may not be sufficient to control the disease in older children (>2 years) with advanced disease, frequently encountered in Indian settings.[46,62]

Combined trabeculotomy and trabeculectomy (CTT)

CTT involves performing trabeculectomy combined with Harm’s assisted sectoral ab externo trabeculotomy. Usually, the authors prefer limbus-based trabeculectomy in order to avoid early postoperative leakage from limbal wounds and close the conjunctiva with absorbable sutures. The scleral flap is fashioned in the shape of either a triangle or a rectangle and closed with either absorbable or nonabsorbable suture based on surgeon’s preference. CTT has stood the test of time with several authors repeatedly reporting favorable long-term outcomes in Indian children with PCG.[42,63] Mandal et al.[64] reported excellent IOP control, favorable visual outcomes, and a low rate of anesthetic complications with primary CTT performed in Indian children within 1 month of age. The survival rate at 12, 24, and 36 months for complete success for IOP control was reported to be 89.4%, 83.6%, and 71.7%, respectively. In another retrospective study of 220 eyes with primary congenital glaucoma (PCG), Mandal and associates found that primary (CTT) achieved sustained intraocular pressure (IOP) control in 44.5% of cases over 20 years, with moderate long-term visual outcomes and a low reoperation rate.[63] A large cohort of 653 patients with PCG in India was also studied by Mandal et al.,[42] who reported that primary CTT without mitomycin-C provided effective long-term IOP control, with a 21.6% complete success rate at 19 years. While CTT proved safe, over half of patients had moderate to severe visual impairment or blindness at final follow-up, highlighting the importance of early detection and intervention. In another study from northern India, Dubey S et al.[65] found promising outcomes for CTT with mitomycin-C (MMC) and releasable suture. The authors found that MMC improves the overall success of the procedure, while releasable suture decreases the risk of postoperative complications, especially those associated with antimetabolites. In another study from India, Agarwal et al.[66] found that in high-risk cases of congenital glaucoma undergoing CTT, a single 4-minute intraoperative MMC exposure at a concentration of 0.2 mg/ml controlled postoperative IOP as effectively as 0.4 mg/ml, while resulting in a lower incidence of complications and thin-walled blebs. However, due to the high rate of bleb-related infections, bleb thinning, and other long-term complications, the use of antimetabolites in the first surgery of young children with PCG must be met with caution.[67] Vimalanathan et al.[68] evaluated long-term outcomes of surgical intervention in children with PCG. The success of CTT, though 77.8% at 1 year, declined to 16.6% at 15 years, highlighting the need for lifelong follow-up despite initial control.

Currently, CTT is the procedure of choice in advanced cases of PCG in the Indian population.

Repeat surgical intervention

Despite all precautionary measures, repeat surgical intervention(s) may be required in up to 11% of operated PCG eyes.[69] Currently, there is no common consensus on the management of refractory PCG after initial failed procedures in the Indian population. However, in these cases, several glaucoma surgeons prefer a repeat trabeculectomy (with or without trabeculotomy) or implantation of Glaucoma Drainage Devices (GDDs).[70]

GDDs are especially beneficial in children who have had multiple failed surgeries, including trabeculectomy, and are at a higher risk of conjunctival scarring.[71] The reported success rates of Ahmed glaucoma valve (AGV) (New World Medical, Inc, California, USA) and Baerveldt glaucoma implant (BGI) (Johnson and Johnson Vision, Chicago, USA) in PCG are 53.4% and 78.8%, respectively, with BGI being associated with lower IOP, fewer glaucoma medications, and significantly higher success rates on long-term follow-up.[72] The Aurolab aqueous drainage implant (AADI) (Aurolab, Madurai, India) – a low-cost, nonvalved, Indian GDD – has also shown promising results in refractory pediatric glaucoma until 2 years postoperative period.[73,74] However, there are no studies evaluating the outcomes of GDD in Indian children with PCG.

Comparative studies have shown that both pediatric and adult patients experience significant IOP reduction and glaucoma medication use post-GDD placement. Pediatric patients have been found to have a higher rate of encapsulation and endophthalmitis as compared to adults, who were more prone to corneal decompensation.[75] In terms of device selection, studies comparing AGV and Baerveldt implants suggest that Baerveldt may offer more sustained IOP control with fewer complications in children.[76] Senthil et al.[77] compared the low-cost nonvalved AADI with the AGV in 116 eyes of children with refractory pediatric glaucoma in India. Both devices had similar qualified success and complication rates at 1 and 3 years. However, AADI showed significantly higher complete success (41.8% vs. 13.7%), better IOP control, fewer medications, and a lower incidence of hypertensive phase. Nonvalved GDDs have been shown to provide superior IOP control with fewer failure rates but at the cost of increased risk for hypotony, highlighting the need for individualized treatment plans based on patient-specific factors.[78]

When choosing a GDD for pediatric patients, the implant size is selected as per the size of the eye. Moreover, the anatomical peculiarities of PCG eyes, such as stretched limbus and thin sclera, can make the surgery technically more challenging as compared to adults. This necessitates the use of grafts, such as autologous sclera, corneoscleral, pericardial, dura mater, or buccal membrane grafts, to prevent tube erosion.[79] Corneoscleral grafts are readily available, while corneal grafts provide better cosmesis.

It is also crucial to preoperatively plan the position of the tube within the eye.[80] Lens status plays a crucial role in deciding tube placement. Sulcus placement is preferred in pseudophakic/aphakic eyes to reduce the risk of corneal touch, while the anterior chamber is typically chosen for phakic eyes to prevent cataractous changes. Furthermore, in children, the expanding globe size, especially when associated with buphthalmos, may lead to tube extrusion or corneal touch. Therefore, longer intracameral tube segments are preferred in young patients with glaucoma to accommodate future growth of their eyes. Younger age of onset, younger age at the time of surgery, and history of previous ocular surgeries are also identified risk factors for tube erosion in children.[80]

As adjuvants, antimetabolites are known to enhance trabeculectomy outcomes in refractory congenital glaucoma,[81] but their utility with GDDs in children is debatable, with respect to Mitomycin-C and anti-vascular endothelial growth factors.[82,83] Between shunts and incisional surgeries used as secondary interventions, GDDs are reported to have better long-term survival compared to CTT in eyes with failed glaucoma surgeries. Conversely, CTT offers the advantage of allowing the possibility of repeat surgical procedures.[84] However, GDD in the pediatric population is associated with a higher rate of tube malposition, tube erosion, corneal touch, and endophthalmitis as compared to adults.[85] Reduced scleral rigidity in buphthalmic eyes also increases the risk of hypotony-related complications with GDDs. Currently, there is a paucity of evidence in the literature on the efficacy and longevity of repeat trabeculectomy and GDD in refractory PCG; therefore, superiority of one over the other and their specific indications are uncertain.

Cyclodestructive procedures

Cyclodestructive procedures involve causing targeted thermal destruction of the ciliary body to reduce aqueous humor production when other filtration surgeries fail, thus subsequently reducing IOP. However, these procedures are less predictable in the pediatric population and are reserved for severe refractory glaucoma in cases with poor visual potential or painful blind eyes as the primary treatment involves increasing aqueous outflow rather than decreasing its production. Diode laser cyclophotocoagulation (DLCP) may be performed by either an external or endoscopic approach.[86] Although it is the most widely performed cyclodestructive procedure, DLCP often requires repeat interventions in refractory pediatric glaucoma. Active regeneration of ciliary body epithelium in children lowers the success rate of GDD in them, as compared to adults.[87] Moreover, an important aspect of DLCP is transillumination. DLCP transillumination in children with congenital glaucoma is often unreliable because corneal/media opacity, thin ectatic sclera, and grossly distorted anterior segment anatomy make localization of the ciliary body inaccurate, leading to patchy or inadequate treatment and increased risk of complications such as hypotony, lens/retinal damage, or perforation. A low-cost trans-corneal transillumination-aided DLCP is widely used in India to overcome these limitations.[88] Micropulse DLCP is an upcoming modality found to have safe and encouraging intermediate results in these eyes.[89] In an initial report, Ariga et al.[90] found a success rate of 89.1% with micropulse trans-scleral DLCP in refractory glaucoma in Indian eyes. A prospective study compared transscleral micropulse (MP-CPC) and continuous wave (CW-CPC) cyclophotocoagulation in refractory pediatric glaucoma; both modalities effectively reduced IOP, but MP-CPC showed fewer complications and a higher, though not statistically significant, success rate (71% vs. 46%), suggesting it may be a safer option for repeated treatments in children.[91] However, long-term results of these modalities, especially in PCG, are still awaited. Endocyclophotocoagulation has also been found to be moderately effective to manage difficult pediatric glaucoma, but its results in Indian subpopulation are yet to be reported.[92] Moreover, utility of ECP is limited in phakic patients due to the risk of cataract formation.

Cyclocryotherapy, although effective in lowering IOP, is not commonly employed in pediatric glaucoma due to high risk of severe postoperative pain and devastating complications such as retinal detachment (7.8%) and phthisis bulbi (7.8%), with aniridia eyes being more susceptible (50% vs 11% nonaniridia eyes, P < 0.05).[93]

A national survey on the preferred practices in the Indian Pediatric Glaucoma Society highlighted a strong preference for combined trabeculotomy–trabeculectomy in hazy corneas and goniotomy in clear corneas, with notable variability in mitomycin-C use and timing of bilateral surgeries.[94] Fig. 3 illustrates the recommended algorithm for surgical management in PCG, formulated based on the comprehensive review of literature and preferred practices best suited to the Indian population.

Figure 3.

Recommended algorithm for surgical management in eyes with primary congenital glaucoma in the Indian setting. *Corneal clarity can be improved with epithelial debridement if the edema is confined to the epithelial layer. However, stromal edema will not resolve with this maneuver. (Abbreviations: CTT: Combined Trabeculotomy and Trabeculectomy; GATT: Gonioscopy-assisted transluminal trabeculotomy; GDD: Glaucoma Drainage Devices; IOP: Intraocular pressure; PCG: Primary Congenital Glaucoma; Re-Trab: Repeat Trabeculectomy)

Postoperative follow-up

Postoperative follow-up of children with PCG is crucial to ensure successful long-term outcomes. Alarmingly, the International Study of Childhood Glaucoma found that Indian children had a disproportionately high loss to follow-up rate as compared to other ethnicities.[95] Therefore, it is essential to educate the care-givers regarding the nature of the disease and the requirement of regular follow-up visits.

The frequency of postoperative follow-up visits depends on the stability of the disease, typically ranging from monthly during the initial postoperative period and to longer intervals as the condition stabilizes. Follow-up assessment must include visual acuity, IOP, anterior segment and posterior segment evaluation for optic nerve status, and peripheral retinal screening in children with high myopia. Specular microscopy must be considered as a significant decrease in corneal endothelial cell count and morphology has been noted postoperatively in children operated for PCG.[96] AL should also be monitored in young children as globe elongation with consequent development of progressive myopia is another indicator of progression of the disease.[63] Additionally, the odds of having pathological retinal degenerations are 14 times higher in eyes with AL ≥26 mm than in eyes with AL <26 mm,[97] making peripheral retinal screening mandatory for eyes with AL ≥26 mm on follow-up.

Once these children are older, visual fields should be assessed. However, visual field testing involves a prolonged learning curve to get a reliable visual field by standard automated perimetry. Various other forms of perimetry like those with handheld and portable units like iPad-based perimetry (MRF), smartphone-based perimetry, and head-mounted perimeters (IMO or VisuALL) provide easy and reliable alternatives.[98] Annual refraction and amblyopia management is essential.

Furthermore, monitoring for late-onset complications such as cataractogenesis, bleb failure/leakage, and bleb-related infections, among others, is essential, emphasizing on the importance of adherence to follow-up schedules and prescribed therapies.

Long-term outcomes

Long-term outcomes of PCG depend on several factors such as the age of onset and presentation, laterality, clinical features, and number of surgeries required to control IOP. Infantile PCG has better long-term visual outcomes than neonatal PCG.[99] Moreover, unilaterality is associated with poorer visual outcomes due to dense amblyopia. In their ambispective study, Sihota et al.[100] identified a baseline and/or final cup-to-disc ratio (CDR) >0.8, the need for two or more medications or repeat glaucoma surgery, and female sex as risk factors for the development and increased severity of glaucomatous visual field defects (VFD) in children with PCG. Another study from India found that in children with unilateral PCG, approximately one-third of the unaffected fellow eyes eventually develop the disease, typically after a period of 5 years or more.[101] Larger CDR at follow-up in the fellow eye is a strong predictive factor for this progression.

Eyes with higher IOP at presentation and larger CDR have a higher risk of failure after the first surgery.[102] Additionally, longer AL at the time of presentation is also predictive of poorer IOP control despite intervention.[103] Additionally, a longer diagnostic delay and more surgeries are associated with a poorer prognosis.[104]

Discussion

As per the current evidence, the choice of surgery in PCG depends on several factors such as the child’s age, corneal clarity, disease severity, history of any previous interventions, and surgeon’s preference and expertise. It is essential to choose procedures that are not only efficacious and safe but also cost-effective, reliable, and repeatable and can be performed with the limited resources available within our healthcare setting. While devices such as illuminated microcatheter and Trab 360 may offer excellent results, issues related to availability and cost arise. Alternatives, especially suture-GATT, prove to be a safe and equally effective alternative providing optimum IOP control with circumferential treatment in young children with PCG. However, GATT is limited by the need for adequate visualization and accurate cannulation of SC, making it less practical in advanced disease or in eyes with severely hazy cornea. In such cases, ab externo trabeculotomy or CTT is particularly advantageous, providing adequate IOP control but at the cost of an increased surgical complexity and a higher risk of complications. GDDs and cyclodestructive procedures, while typically reserved for refractory cases, offer viable options when conventional surgeries fail, though they carry risks of hypotony, phthisis, or significant inflammation. Although low-cost Indian GDD has shown promising outcomes, the long-term results are yet to be seen in children.

This review focuses specifically on the management of PCG in the Indian population, where disease burden, patterns of presentation, and health-system constraints differ from Western cohorts. By reviewing and analyzing data from multiple Indian centers and practice settings, it provides a context-specific overview of surgical choices, timing, and outcomes that is directly applicable to local clinical practice. The review also integrates epidemiological, genetic, clinical, and surgical aspects and highlights practical issues such as combined procedures, repeat surgeries, and long-term follow-up, thereby helping to frame management strategies for PCG in India. Several limitations must be considered while interpreting these findings. The available Indian studies are heterogeneous with respect to case definition, age at presentation, severity, prior treatment, surgical technique, outcome measures, and duration of follow-up, which limits direct comparability and precludes robust quantitative synthesis. Most reports are retrospective case series from single high-volume tertiary centers, with risks of selection bias, incomplete documentation of confounders, and limited generalizability to smaller or resource-limited settings. Furthermore, newer data on refinements in angle surgery, combined procedures, and adjunctive imaging published after the search cutoff may alter or refine some of the conclusions of this review.

Conclusion

Primary congenital glaucoma remains a major cause of preventable childhood blindness in India, with distinctive challenges related to late presentation and resource constraints. The available Indian data suggest that timely angle surgery offers the best outcomes when corneal clarity permits, while trabeculectomy, combined procedures, and drainage devices are valuable in advanced or refractory disease. Early diagnosis, appropriate procedure selection, and sustained follow-up emerge as consistent determinants of success. Strengthening multicentric collaborative research, standardizing outcome reporting and improving systems for early detection and long-term care will be key to reducing the visual burden of PCG in Indian children.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.