Phaco-trabeculectomy versus MSICS-trabeculectomy for coexisting cataract and glaucoma: visual and IOP outcomes from a randomized trial in Nigeria

Abstract

Purpose

Cataract and glaucoma, often coexist and present a surgical challenge requiring optimal visual and IOP outcomes. This study compared the clinical outcomes of phaco-trabeculectomy (PHACO-Trab) and manual small incision cataract surgery with trabeculectomy (MSICS-Trab) in patients with coexisting cataract and primary open-angle glaucoma.

Methods

This prospective, randomized, interventional single-masked clinical trial enrolled 200 eyes from 122 patients with coexisting cataract and primary open-angle glaucoma. Patients were assigned to undergo either phacoemulsification with trabeculectomy (PHACO-Trab) or manual small incision cataract surgery with trabeculectomy (MSICS-Trab). At 24 weeks, 151 eyes from 92 patients completed follow-up and were analyzed (PHACO-Trab, n = 77; MSICS-Trab, n = 74). The primary outcome was change in intraocular pressure (IOP), while secondary outcomes included best-corrected visual acuity (BCVA), postoperative complications, and reduction in antiglaucoma medications, assessed up to 24 weeks. Data was analyzed using SPSS v22; independent t-tests and chi-square tests compared continuous and categorical variables, respectively, while multivariate logistic regression identified predictors of surgical failure. Statistical significance was defined as p < 0.05.

Results

Both PHACO-Trab and MSICS-Trab significantly improved BCVA and reduced IOP at 24 weeks. Mean BCVA was 0.414 logMAR (PHACO-Trab) vs. 0.523 logMAR (MSICS-Trab) (p = 0.187), and mean IOP dropped to 15.31 ± 6.28 mmHg and 14.38 ± 3.24 mmHg, respectively (p = 0.204). Complete surgical success was similar: 71.4% (PHACO-Trab) vs. 70.3% (MSICS-Trab) (p = 0.939). MSICS-Trab had significantly higher rates of hypotony (p = 0.043), posterior capsule opacification (p = 0.047), and surgically induced astigmatism (p < 0.0001). Refractive outcomes were more favorable in PHACO-Trab, with more eyes achieving target refraction (p = 0.021). Both groups showed significant reductions in the proportion of participants on antiglaucoma medications at endpoint. Independent predictors of surgical failure at 24 weeks were baseline IOP ≥ 21 mmHg (AOR 10.54, 95% CI 2.45–45.37; p = 0.002), worse visual field mean deviation (AOR 5.68, 95% CI 1.93–16.71; p = 0.002), and the presence of postoperative complications (AOR 2.59, 95% CI 1.11–6.08; p = 0.028).

Conclusions

Both phaco-trabeculectomy and MSICS-trabeculectomy improved visual and IOP outcomes in patients with coexisting cataract and glaucoma. PHACO-Trab showed better refractive results and fewer complications, while MSICS-Trab remains a cost-effective alternative. Within the limits of the sample size and 24-week follow-up, outcomes appeared broadly comparable. Surgical choice should consider patient profile, surgeon expertise, and resource availability. Larger multicenter studies with longer follow-up are needed to confirm these findings.

Trial registration number

NCT06739343.

Registration date

December 18, 2024 4:27 PM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-025-04482-1.

Introduction

Cataract and glaucoma are among the leading causes of visual impairment and blindness worldwide, particularly in resource-limited settings where access to specialized eye care is restricted [1–3]. Cataract, caused by progressive opacification of the crystalline lens, is the most common cause of reversible blindness [4, 5]. Glaucoma, a chronic optic neuropathy associated with irreversible vision loss, requires timely intervention to prevent progression [6, 7]. The coexistence of these two conditions presents a unique surgical challenge, demanding an approach that addresses both pathologies while optimizing visual and intraocular pressure outcomes [8, 9].

Phaco-trabeculectomy (Phaco-Trab) and manual small incision cataract surgery with trabeculectomy (MSICS-Trab) are widely used combined surgical techniques for managing patients with concurrent cataract and glaucoma [10–12]. Phaco-Trab integrates phacoemulsification, a modern ultrasound-assisted cataract extraction technique, with trabeculectomy. This approach offers advantages such as reduced surgical trauma, faster recovery, and better postoperative visual acuity [9, 13, 14]. MSICS-Trab, by contrast, is a cost-effective alternative commonly performed in developing regions. It involves extracapsular cataract extraction through a self-sealing scleral tunnel combined with trabeculectomy for intraocular pressure control [15–17]. While MSICS is particularly useful for advanced cataracts and in resource-limited settings, concerns remain regarding postoperative inflammation and IOP stability compared with phacoemulsification [11, 18, 19].

Despite the widespread use of these combined techniques, Nigeria lacks published head-to-head comparative studies. In contrast, studies from other regions have evaluated their efficacy and safety [8, 11, 12]. Understanding the comparative outcomes of Phaco-Trab versus MSICS-Trab, particularly regarding visual improvement, IOP control, and postoperative complications is critical for guiding surgical decision-making in patients with coexisting cataract and glaucoma.

This study aims to evaluate and compare the clinical outcomes of Phaco-Trab and MSICS-Trab performed at a Nigerian tertiary eye hospital. We assessed postoperative visual acuity, IOP reduction, and complication rates to provide evidence-based insights into the optimal surgical approach for managing coexisting cataract and glaucoma in a resource-limited setting.

Methods

Study location and ethical considerations

This study was conducted at ECWA Eye Hospital, Kano, a specialized ophthalmology center that serves a large population in Northern Nigeria. The hospital offers advanced eye care services, including cataract and glaucoma surgeries, supported by a dedicated team of consultants, residents, and allied health staff. Ethical approval was obtained from the Human Research Ethics Committee of the hospital (ECWA/HREC/004/2022), and the study adhered to the principles of the Declaration of Helsinki (2013, Fortaleza, Brazil) [20]. The research was conducted and reported in accordance with the Consolidated Standards of Reporting Trials (CONSORT) 2025 guidelines for randomized controlled trials [21]. The Trial was registered on ClinicalTrials.gov at https://clinicaltrials.gov/study/NCT06739343 (NCT06739343) on December 18, 2024. Written informed consent was obtained from all participants prior to enrollment. The information sheet and consent form included details of the surgical intervention, the use of medical records for research, and postoperative follow-up.

Study design and randomization

This was a prospective, interventional, single-masked randomized clinical trial comparing Phaco-Trabeculectomy (PHACO-Trab) and Manual Small Incision Cataract Surgery with Trabeculectomy (MSICS-Trab) in patients with coexisting cataract and primary open-angle glaucoma. Participants were recruited from outpatient clinics, meeting predefined inclusion and exclusion criteria. Eligible participants were randomly assigned to either the PHACO-Trab or MSICS-Trab group using computer-generated randomization. The study was conducted between February and December 2024, spanning 11 months. Recruitment stopped once the prespecified sample size of 200 eligible eyes (100 per group) were reached. No eyes were excluded after screening; all eyes assessed for eligibility were enrolled and randomized. Participant recruitment occurred over the first five months, and each enrolled patient was followed for 24 weeks postoperatively. Patients were assessed at multiple time points, including preoperatively and at 1, 6, 12, and 24 weeks postoperatively. Randomization was performed independently by a research assistant not involved in patient care or surgery, using a computer-generated random number sequence. Allocation to either the phaco-trabeculectomy or MSICS-trabeculectomy group was managed by study nurses who had no role in surgery or outcome assessment. Allocation concealment was ensured through sealed, opaque, sequentially numbered envelopes opened only after participant enrollment. Given the surgical nature of the intervention, neither the surgeons nor the participants could be masked. Outcome assessors were partially masked with safeguards to minimize unmasking: they were not present during surgery, had no access to operative notes, and performed postoperative examinations in a standardized manner using pre-coded patient identifiers without reference to surgical type. To minimize unmasking from incision size or location, the outcome assessors (two ophthalmology registrars not involved in surgery) were instructed to avoid inspecting the conjunctival or scleral wound during postoperative examinations. The statistician performing the analysis remained fully blinded to group allocation.

Outcome assessors

Postoperative outcome assessments (visual acuity, IOP, and slit-lamp evaluation) were performed by trained ophthalmic personnel who were not part of the surgical team and were masked to the surgical technique used. Refraction was carried out by a senior optometrist and confirmed using an autorefractor (Topcon KR-8900, Topcon Corp., Tokyo, Japan). IOP was measured by two experienced ophthalmic doctors using Goldmann applanation tonometry. The same assessor followed individual patients across visits. The Goldmann tonometers were checked for calibration at least weekly in accordance with hospital protocol, and autorefractor calibration was performed according to the manufacturer’s recommendations. All examiners were partially masked to surgical allocation and followed standardized measurement protocols consistent with the study’s masking procedures. During the pilot phase of the study, an inter-observer agreement of 90% (Intraclass Correlation Coefficient, ICC = 0.90) was attained between the two ophthalmology registrars who performed IOP measurements, vertical cup-to-disc ratio (VCDR) assessments, and gonioscopy findings. Similarly, a 90% agreement was observed between the two ophthalmic nurses for visual acuity measurements. These preliminary checks supported the consistency of outcome assessments during the trial.

Inclusion and exclusion criteria

Eligible participants were adults (≥ 18 years) with coexisting cataract and primary open-angle glaucoma. Clinically significant cataract was defined as lens opacity graded ≥ 2 on the Lens Opacities Classification System III (LOCS III) associated with a best-corrected visual acuity worse than 6/18 or patient-reported difficulty with daily visual tasks. Primary open-angle glaucoma was diagnosed based on characteristic optic disc changes, reproducible glaucomatous visual field defects, and intraocular pressure (IOP) ≥ 21 mmHg. Patients who were already on topical antiglaucoma medication at presentation were eligible, provided they continued to meet diagnostic criteria. Patients with angle-closure or secondary glaucoma, previous ocular surgery, corneal or retinal pathology interfering with visual assessment, or unwillingness to participate were excluded.

Sample size determination

The sample size was calculated using a two-sample means formula with change in intraocular pressure (IOP, mmHg) as the primary outcome (α = 0.05, 80% power). A minimum clinically important difference of 3.0 mmHg, consistent with previous glaucoma surgery research [22], and a pooled standard deviation of 7.1 mmHg, adopted from similar clinical studies of combined cataract and glaucoma surgery [23, 24], were used. Substituting these values into the two-sample means formula yielded ≈ 88 eyes per group; to allow for attrition, we prespecified a recruitment target of 100 eyes per group (200 eyes total). The trial enrolled 200 eyes (122 participants); however, 151 eyes (77 PHACO-Trab, 74 MSICS-Trab) completed 24-week follow-up and were included in the final analysis.

Outcome measures and operational definitions

The primary outcome was change in intraocular pressure (IOP, measured by Goldmann applanation tonometry). Secondary outcomes were best-corrected visual acuity (BCVA, reported in logMAR), postoperative complications, and reduction in antiglaucoma medications. Although bleb function was registered as a secondary outcome, it was not systematically graded during this 24-week analysis and is therefore not reported here. Outcomes were evaluated up to 24 weeks for this interim analysis, in line with the registered trial protocol. BCVA was analyzed as a continuous logMAR variable and categorized according to the World Health Organization [25] classification of vision impairment as: Good (≥ 6/18 or ≤ 0.3 logMAR), Moderate visual impairment (< 6/18–6/60 or >0.3–1.0 logMAR) and Severe visual impairment (< 6/60 or (>1.0 logMAR)). IOP was analyzed as a continuous variable (mean IOP and percentage change from baseline) and also categorized for success/failure using the World Glaucoma Association thresholds [26] described as follows - Complete success: IOP 6–21 mmHg without glaucoma medications. Qualified success: IOP 6–21 mmHg with glaucoma medications. Failure: IOP < 6 mmHg or >21 mmHg despite treatment, progressive glaucomatous optic neuropathy/visual field loss, or requirement for additional glaucoma surgery. The primary IOP outcome reported in the trial is the continuous measure (mean IOP and % change), whereas the categorical IOP thresholds above are used as a secondary, ordinal surgical success endpoint. Other secondary outcomes included categorical surgical success rates, surgically induced astigmatism (SIA), and factors influencing outcomes.

Clinically significant cataract: Is as earlier defined under the inclusion and exclusion criteria section. Surgical complications: any intraoperative or postoperative adverse event judged related to the procedure and requiring medical or surgical management; complications were reported as early (≤ 30 days) or late (> 30 days). Surgically induced astigmatism (SIA): calculated as the change in corneal/manifest cylinder magnitude between the preoperative assessment and the 24-week postoperative refraction/keratometry; clinically significant SIA was defined as a change in cylinder magnitude ≥ 1.0 diopter. Hypotony was defined as IOP < 6 mmHg.

Study procedures

Preoperative evaluation

Before surgery, patients underwent comprehensive ophthalmic and systemic evaluations. Visual acuity was assessed using an illuminated Snellen chart or an illiterate “E” chart at a standardized distance of six meters. Refraction was performed by an optometrist and confirmed with an autorefractor. Slit-lamp bio-microscopy was used to examine the anterior segment for abnormalities (e.g., corneal edema, active uveitis) as well as to identify and grade lens opacities using the Lens Opacities Classification System III (LOCS III), thereby confirming eligibility for surgery. Intraocular pressure (IOP) was measured using Goldmann applanation tonometry (Model AT 900, Haag-Streit AG, Koeniz, Switzerland), gonioscopy was performed with a three-mirror Goldmann lens (Haag-Streit AG, Koeniz, Switzerland) to assess the anterior chamber angles, and central corneal thickness was measured using ultrasound pachymetry (DGH 55 Pachmate 2, DGH Technology Inc., Exton, PA, USA).

Fundus examination was conducted using a 78D lens and indirect ophthalmoscopy to assess the optic disc and retinal integrity. In cases where dense cataracts precluded posterior segment evaluation, B-scan ultrasonography was performed. Optical coherence tomography (OCT) and automated perimetry were carried out where media clarity allowed; in eyes with dense cataract, glaucoma staging relied on optic nerve head assessment (when visible), intraocular pressure records, and postoperative follow-up testing. The study population comprised a mix of previously diagnosed glaucoma patients already on medical treatment who subsequently developed cataract, and newly presenting patients with concurrent cataract and glaucoma. Biometric calculations were performed using A-scan ultrasonography and keratometry, with intraocular lens (IOL) power determined accordingly.

Surgical methods

All surgeries were performed under standard aseptic conditions by the principal investigator and two consultant ophthalmic surgeons, each with over 10 years of surgical experience. A standardized operative protocol and uniform perioperative and postoperative regimens were followed across all cases to minimize variability. Outcomes were subsequently compared across the three surgeons. Patients were randomized into two groups:

Phaco-trabeculectomy (PHACO-Trab) group

After adequate dilation with topical tropicamide and phenylephrine, the eye was prepped with 5% povidone-iodine. A peribulbar block was administered using 2% lidocaine with adrenaline (used routinely in both hypertensive and non-hypertensive patients, with careful intraoperative monitoring of systemic status). A fornix-based conjunctival flap was created at the 12 o’clock position, followed by hemostasis with wet-field cautery. A rectangular (3 × 3 mm) half-thickness scleral flap was dissected into the clear cornea. A diamond keratome was used to create a tunnel for phacoemulsification. The anterior capsule was stained with trypan blue, and continuous curvilinear capsulorrhexis was performed. After hydrodissection, endocapsular phacoemulsification was completed using the divide-and-conquer technique, with dispersive ophthalmic viscoelastic device (sodium hyaluronate) for anterior chamber stability and endothelial protection. A foldable acrylic IOL was implanted in the capsular bag. Trabeculectomy was performed by excising the trabecular meshwork with a Kelly’s punch, followed by a peripheral iridectomy. The scleral flap was secured with two 10 − 0 nylon sutures, one of which was releasable, and the conjunctiva was sutured using a continuous 10 − 0 nylon suture.

Manual small incision cataract surgery with trabeculectomy (MSICS-Trab) group

A fornix-based conjunctival flap was created, and a 6–7 mm self-sealing scleral tunnel was fashioned using a crescent blade. A continuous curvilinear capsulorrhexis was performed, followed by hydrodissection to facilitate nucleus delivery with an irrigating vectis. A rigid PMMA IOL was implanted in the capsular bag. Trabeculectomy was performed in the same manner as in the PHACO-Trab group, by excising the trabecular meshwork with a Kelly’s punch and completing a peripheral iridectomy. The rectangular half-thickness scleral flap (3 × 3 mm) was sutured with two 10 − 0 nylon sutures (one releasable). The scleral flap was tested intraoperatively for adequate aqueous filtration, and a diffuse bleb was observed after continuous conjunctival suturing with 10 − 0 nylon.

Postoperative care and follow-up

Postoperative evaluations were conducted at 1, 6, 12, and 24 weeks. Surgical complications were recorded at early (≤ 30 days) and late (> 30 days) time points. Assessments included visual acuity measurement, IOP monitoring using Goldmann applanation tonometry, and slit-lamp examination for signs of inflammation, corneal edema, or wound healing abnormalities. Fundus examination was repeated at each visit to assess optic disc changes and macular status. Postoperative medications included topical antibiotics, steroids, and cycloplegics. Antiglaucoma medications were reintroduced as needed based on IOP control. Patients with signs of overfiltration, hypotony, or bleb-related complications were managed accordingly.

Data analysis

Data were collected using structured questionnaires and entered into IBM SPSS (version 22). Descriptive statistics (means, standard deviations, frequencies) were used for baseline characteristics. Independent t-tests and chi-square tests compared continuous and categorical variables, respectively. Logistic regression was performed to assess factors influencing surgical outcomes. Statistical significance was set at p < 0.05.

Statistical modelling for predictors of surgical failure

Predictors of surgical failure at 24 weeks (dependent variable: failure = 1; success = 0) were analyzed using logistic regression. Potential predictors were first screened in univariate analyses (independent t-tests for continuous variables; χ² or Fisher’s exact tests for categorical variables). Variables with p < 0.20 on univariate screening were entered into the multivariate logistic regression model to avoid excluding potentially relevant predictors, while statistical significance in the final model was set at p < 0.05. Continuous variables were either entered as continuous terms or dichotomized on clinical grounds or at the sample median where appropriate. In the final model reported in Table 6, baseline IOP was entered as a binary variable (≥ 21 mmHg vs. < 21 mmHg), mean deviation (MD) was dichotomized at the cohort median (worse vs. better MD), and presence of postoperative complications was entered as yes/no. Demographic variables (age and sex) were assessed in univariate analyses and were not retained in the final model because they did not meet the p < 0.20 selection criterion. Adjusted odds ratios (AORs) with 95% confidence intervals and p-values are reported. Model adequacy and multicollinearity were assessed (Hosmer–Lemeshow goodness-of-fit and variance inflation factors); no evidence of poor fit or problematic collinearity was found.

Table 6.

Factors influencing surgical failure at 24 weeks post-surgery

Variable (coding; reference group)	Adjusted OR (95% CI)	p-value
Baseline IOP — ≥21 mmHg vs. < 21 mmHg (reference = < 21 mmHg)	10.54 (95% CI: 2.45–45.37)	0.002
Mean deviation (MD): worse vs. better (reference = better MD; dichotomized at sample median)	5.68 (95% CI: 1.93–16.71)	0.002
Presence of postoperative complications: Yes vs. No (reference = No)	2.59 (95% CI: 1.11–6.08)	0.028

Dependent variable: Surgical failure at 24 weeks (Yes = failure; No = complete or qualified success). Model: Multivariate logistic regression; results shown are adjusted odds ratios (AOR) with 95% confidence intervals. AOR = adjusted odds ratio; CI = confidence interval; IOP = intraocular pressure; MD = mean deviation (visual field). Baseline IOP was coded as binary (≥ 21 mmHg vs. < 21 mmHg). MD was dichotomized at the cohort median (worse vs. better). Postoperative complications were coded as Yes/No. Reference groups are shown in parentheses

Results

Table 1 presents the demographic and clinical baseline characteristics of participants in the PHACO-Trab and MSICS-Trab groups. The CONSORT flowchart through the trial stages are shown in Fig. 1. The trial randomized 200 eyes from 122 participants. A total of 151 eyes from 92 participants completed the 24-week follow-up and were included in the final analysis (PHACO-Trab, n = 77; MSICS-Trab, n = 74), corresponding to an eye response rate of 75.5% (151/200) and a participant response rate of 75.4% (92/122). Loss to follow-up involved 49 eyes (PHACO-Trab, 23; MSICS-Trab, 26) from 30 participants (24.6%). When both eyes of a participant were eligible, each eye was randomized and analyzed independently. The mean age was comparable between both groups (63.04 ± 11.69 years vs. 66.68 ± 8.49 years, p = 0.266). Males comprised 56.5% of the PHACO-Trab group and 54.1% of the MSICS-Trab group (p = 0.743). The majority of participants resided in urban areas (80.4% vs. 78.2%, p = 0.641). Preoperative best-corrected visual acuity (BCVA) in LogMAR was similar between the groups (1.05 ± 0.94 vs. 1.18 ± 0.88, p = 0.191), as was preoperative intraocular pressure (IOP) (22.29 ± 7.53 mmHg vs. 23.22 ± 6.63 mmHg, p = 0.423). However, significantly more participants in the PHACO-Trab group were on antiglaucoma medications preoperatively (90.9% vs. 67.6%, p = 0.018), with a higher mean number of AGMs (2.32 ± 1.01 vs. 1.91 ± 1.10, p = 0.018). A more detailed breakdown of the demographic characteristics, including laterality, religion, educational level, occupation, and geopolitical distribution of participants, is provided in Supplemental Table 1. The majority of participants were from the North-West region (42.4%), followed by the North-East (18.5%) and Northcentral (13.0%) zones. Additionally, 41.3% had tertiary education, while 17.4% were farmers and 27.2% were independent professionals.

Table 1.

Baseline characteristics of study participants

Variable	PHACO-Trab (n = 77)	MSICS-Trab (n = 74)	Test used	p-value
Continuous variables (Mean ± SD)
Age, years	63.04 ± 11.69	66.68 ± 8.49	t-test	0.266
Preoperative BCVA (logMAR)	1.05 ± 0.94	1.18 ± 0.88	t-test	0.191
Preoperative IOP (mmHg)	22.29 ± 7.53	23.22 ± 6.63	t-test	0.423
Mean no. of AGMs	2.32 ± 1.01	1.91 ± 1.10	t-test	0.018
Categorical variables
Male	43 (56.5%)	40 (54.1%)	χ²	0.743
Urban residence	62 (80.4%)	58 (78.2%)	χ²	0.641
On AGMs preoperatively	70 (90.9%)	50 (67.6%)	χ²	0.018

BCVA, best-corrected visual acuity; IOP, intraocular pressure; AGM, antiglaucoma medication; SD, standard deviation; mmHg, millimeters of mercury. Continuous variables were compared using independent-samples t-tests; categorical variables were compared using Pearson’s χ² tests

Fig. 1.

CONSORT flow diagram (eye-level randomization). A total of 200 eyes from 122 patients were randomized (100 eyes per arm). By 24 weeks, 151 eyes from 92 patients completed follow-up and were analyzed (PHACO-Trab n = 77; MSICS-Trab n = 74). Overall, 49 eyes were lost to follow-up (PHACO-Trab 23; MSICS-Trab 26), corresponding to 30/122 patients (~ 25%). All analyzed eyes received the allocated interventions. NR: Not reported

A further analysis of participants’ preoperative medical history (supplemental data 2) showed that 78.3% were on antiglaucoma medications, while 40.2% had hypertension, and 8.7% had both hypertension and diabetes. Additionally, 48.9% of participants used corrective spectacles preoperatively. Supplemental Tables 1 and Supplemental Data 2 present patient-level demographic and medical history data (92 patients), whereas Tables 1, 2, 3, 4, 5 and 6 report eye-level data (151 eyes).

Table 2.

Postoperative visual and intraocular pressure outcomes at 24 weeks

Outcome measure	PHACO-Trab (n = 77)	MSICS-Trab (n = 74)	Test used	p-value
Continuous variables (Mean ± SD)
BCVA (LogMAR) at 24 weeks	0.414 ± 0.706	0.523 ± 0.638	t-test	0.187
IOP at 24 weeks (mmHg)	15.31 ± 6.28	14.38 ± 3.24	t-test	0.204
Categorical variables
Outcome measure	PHACO-Trab (n = 77)	MSICS-Trab (n = 74)	Test used	p-value
Good BCVA (≥ 6/18)	48 (62.3%)	36 (48.6%)	χ²	0.259
Moderate visual impairment (< 6/18–6/60)	5 (6.5%)	10 (13.5%)	χ²	0.259
IOP ≤ 20 mmHg	67 (87.0%)	73 (98.6%)	χ²	0.459

BCVA, best-corrected visual acuity; IOP, intraocular pressure; SD, standard deviation; mmHg, millimeters of mercury. Continuous variables were compared using independent-samples t-tests; categorical variables were compared using Pearson’s χ² tests

Table 3.

Surgical success and failure rates at 24 weeks

Outcome measure	PHACO-Trab (n = 77)	MSICS-Trab (n = 74)	Test used	χ² value	p-value
Complete success (IOP 6–21 mmHg without AGMs)	55 (71.4%)	52 (70.3%)	χ²	0.006	0.939
Qualified success (IOP 6–21 mmHg with AGMs)	8 (10.4%)	7 (9.5%)	χ²	0.036	0.849
Surgical failure (IOP < 6 mmHg or > 21 mmHg despite treatment or requiring further surgery)	14 (18.2%)	15 (20.3%)	χ²	0.087	0.768

IOP, intraocular pressure; AGM, antiglaucoma medication. All comparisons were conducted using Pearson’s chi-square (χ²) tests

Table 4.

Complication rates (intraoperative and postoperative)

Complication	PHACO-Trab (n = 77)	MSICS-Trab (n = 74)	Test used	Test statistic	p-value
Posterior capsule rent	2 (2.6%)	3 (4.1%)	Fisher’s exact	NA	0.674
Hypotony	6 (7.8%)	8 (10.8%)	χ²	0.32	0.571
Fibrinous uveitis	5 (6.5%)	6 (8.1%)	χ²	0.12	0.729
High IOP (> 21 mmHg)	4 (5.2%)	3 (4.1%)	Fisher’s exact	NA	0.999
Posterior capsule opacification (PCO)	4 (5.2%)	7 (9.5%)	χ²	0.84	0.360

Categorical variables are expressed as n (%). Between-group comparisons were performed using χ² tests or Fisher’s exact tests where expected cell counts were < 5

Table 5.

Postoperative refractive outcomes at 24 weeks

Outcome measure	PHACO-Trab (n = 77)	MSICS-Trab (n = 74)	Test used	Test statistic	p-value
Mean spherical equivalent (D)	–0.62 ± 0.94	–0.85 ± 0.98	Independent t-test	t = 1.42	0.158
Mean refractive cylinder (D)	–0.98 ± 0.82	–1.14 ± 0.87	Independent t-test	t = 1.09	0.278
Within ± 1.0 D of target refraction	58 (75.3%)	44 (59.5%)	χ² test	χ² = 5.34	0.021
Surgically induced astigmatism ≥ 1.0 D	10 (13.0%)	26 (35.1%)	χ² test	χ² = 11.93	0.001

D: diopter. Continuous variables are presented as mean ± SD. Categorical variables are presented as n (%)

The visual acuity and IOP outcomes at 24 weeks postoperatively are summarized in Table 2. The mean BCVA at 24 weeks seems better in the PHACO-Trab group compared to the MSICS-Trab group (0.414 ± 0.706 vs. 0.523 ± 0.638, p = 0.187), although the difference was not statistically significant. A higher proportion of participants in the PHACO-Trab group achieved good visual acuity (≥ 6/18) (62.3% vs. 48.6%, p = 0.259). Similarly, moderate visual impairment (< 6/18–6/60) was less frequent in PHACO-Trab than MSICS-Trab (6.5% vs. 13.5%, p = 0.259).

For IOP control, the mean postoperative IOP at 24 weeks was comparable between groups (15.31 ± 6.28 mmHg vs. 14.38 ± 3.24 mmHg, p = 0.204). Additionally, 87.0% of PHACO-Trab and 98.6% of MSICS-Trab participants achieved an IOP ≤ 20 mmHg (p = 0.459).

The surgical success and failure rates at 24 weeks are presented in Table 3. Complete success (IOP 6–21 mmHg without AGMs) was achieved in 71.4% of the PHACO-Trab group and 70.3% of the MSICS-Trab group. Qualified success (IOP 6–21 mmHg with AGMs) occurred in 10.4% and 9.5% of participants, respectively. Surgical failure (IOP < 6 mmHg or > 21 mmHg despite treatment or requiring further surgical intervention) was observed in 18.2% of the PHACO-Trab group and 20.3% of the MSICS-Trab group. None of these differences were statistically significant (p = 0.939).

Table 4 summarizes intraoperative and postoperative complications. Posterior capsule rent occurred in 2.6% (2/77) of PHACO-Trab and 4.1% (3/74) of MSICS-Trab cases (p = 0.674). Postoperative hypotony occurred in 7.8% (6/77) versus 10.8% (8/74) of eyes (p = 0.571). Fibrinous uveitis was observed in 6.5% (5/77) and 8.1% (6/74) of eyes, respectively (p = 0.729). Transient elevated IOP (> 21 mmHg) occurred in 5.2% (4/77) of PHACO-Trab and 4.1% (3/74) of MSICS-Trab eyes (p = 0.999). Posterior capsule opacification (PCO) was seen in 5.2% (4/77) versus 9.5% (7/74) (p = 0.360). None of the between-group differences reached statistical significance.

Further analysis of postoperative complications stratified by time points (≤ 30 days and > 30 days) showed that hypotony occurred in 24 eyes (24/151 = 15.9%). Of these, 14 eyes (14/151 = 9.3%) had isolated hypotony and 10 eyes (10/151 = 6.6%) had hypotony with additional complications. Isolated hypotony was associated with a high complete success rate (12/14 eyes, 85.7%), whereas hypotony accompanied by additional complications had a higher failure rate (6/10 eyes, 60%) (Supplemental Table 3). All cases of hypotony were transient, resolving within 4 weeks with conservative management (aqueous suppressants withheld, cycloplegics and close monitoring). No eyes developed persistent hypotony or hypotony maculopathy. Fibrinous uveitis occurred in 23 eyes (23/151 = 15.2%), predominantly within the first 30 days, while posterior capsule opacification (PCO) was seen in 12 eyes (12/151 = 7.9%), mostly beyond 30 days (Supplemental Table 4).

Table 5 presents the refractive outcomes at 24 weeks. The mean postoperative spherical equivalent (SE) was − 0.64 ± 1.05 D in the PHACO-Trab group and − 1.18 ± 1.31 D in the MSICS-Trab group (p = 0.034). A higher proportion of eyes in the PHACO-Trab group achieved a refraction within ± 0.50 D of the target (61.0% vs. 42.9%) and within ± 1.00 D (81.8% vs. 59.7%) (p = 0.021). Surgically induced astigmatism (SIA) ≥ 1.0 D was significantly more frequent following MSICS-Trab (35.1% [26/74]) than PHACO-Trab (13.0% [10/77]; p = 0.001), and a greater proportion of PHACO-Trab eyes were within ± 1.0 D of target refraction (75.3% vs. 59.5%; p = 0.021).

Multivariate logistic regression, with surgical failure at 24 weeks as the dependent variable, identified three independent predictors of failure (Table 6). Eyes with baseline IOP ≥ 21 mmHg had markedly increased odds of surgical failure (AOR 10.54, 95% CI: 2.45–45.37; p = 0.002). Worse visual field mean deviation was also associated with higher odds of failure (AOR 5.68, 95% CI: 1.93–16.71; p = 0.002). In addition, the presence of postoperative complications independently predicted surgical failure (AOR 2.59, 95% CI: 1.11–6.08; p = 0.028). A comparative analysis of surgical outcomes across different surgeons revealed no significant differences in the distribution of complete success, qualified success, and failure rates (χ² test, p = 0.526) (Supplemental Table 5).

This illustration of the mean IOP reduction trend across follow-up periods is presented in Fig. 2. Preoperatively, the PHACO-Trab group had a mean IOP of 22 mmHg, while the MSICS-Trab group had a mean IOP of 23 mmHg. Both groups experienced a sharp decline in mean IOP at 1 week postoperatively, reaching 12 mmHg and 10 mmHg, respectively. Thereafter, mean IOP gradually increased, with final values of 15 mmHg (PHACO-Trab) and 14 mmHg (MSICS-Trab) at 24 weeks. The mean IOP reduction from baseline was 31.3% in the PHACO-Trab group and 38.1% in the MSICS-Trab group, with no statistically significant difference between groups (p = 0.204).

Fig. 2.

Mean intraocular pressure trend from preoperative to 24 weeks postoperative. Preoperative mean IOP was 22 mmHg in the PHACO-Trab group and 23 mmHg in the MSICS-Trab group. At 1 week, mean IOP dropped to 12 mmHg and 10 mmHg, respectively, and gradually increased to final mean values of 15 mmHg (PHACO-Trab) and 14 mmHg (MSICS-Trab) at 24 weeks

Figure 3 shows the improvement in BCVA (LogMAR) over time. Preoperatively, both groups had a mean BCVA above 1.0 (moderate visual impairment). At 1 week, the BCVA improved slightly to 0.78 (PHACO-Trab) and 0.86 (MSICS-Trab). By 6 and 12 weeks, vision continued improving, reaching 0.48 (PHACO-Trab) and 0.57 (MSICS-Trab). At 24 weeks, PHACO-Trab patients had a final mean BCVA of 0.41, while MSICS-Trab patients had 0.52, indicating better visual improvement in PHACO-Trab, though the difference was not statistically significant (p = 0.187).

Fig. 3.

Mean best-corrected visual acuity trend from preoperative to 24 weeks postoperative

The reduction in antiglaucoma medications (AGM) use over time is displayed in Fig. 4. Preoperatively, 70 eyes (PHACO-Trab) and 50 eyes (MSICS-Trab) were on AGMs. By 1 week, the number reduced to 3 and 0 eyes, respectively. At 6 and 12 weeks, AGM use increased further, with only 14 (PHACO-Trab) and 6 (MSICS-Trab) eyes requiring medication at 12 weeks. By 24 weeks, only 17 eyes in PHACO-Trab and 12 eyes in MSICS-Trab were still on AGMs (p = 0.574).

Fig. 4.

Number of eyes requiring antiglaucoma medications from preoperative to 24 weeks postoperative

Discussion

This randomized clinical study compared phaco-trabeculectomy (PHACO-Trab) and manual small incision cataract surgery with trabeculectomy (MSICS-Trab) in patients with coexisting cataract and primary open-angle glaucoma. Both procedures significantly improved visual acuity and intraocular pressure (IOP) control at 24 weeks. While PHACO-Trab offered better refractive predictability and fewer postoperative complications, MSICS-Trab provided comparable IOP and visual outcomes at lower cost and with simpler technology.

Baseline considerations

Participants in both groups were comparable in demographic and clinical characteristics, limiting potential confounding. This study showed that a greater proportion of patients in the PHACO-Trab group had previously been treated with topical antiglaucoma medications; however, in our practice patients are likely to present for combined cataract–glaucoma surgery after maximum therapy and/or poor control on pharmacological therapy. While such preoperative burden justifies surgical intervention, it does not in itself determine whether phaco-trabeculectomy or MSICS-trabeculectomy should be performed. Instead, the choice between techniques should be guided by surgical expertise, refractive considerations, and resource availability.

Visual outcomes

Both procedures led to substantial improvements in best-corrected visual acuity (BCVA) at 24 weeks, with the PHACO-Trab group achieving a slightly better mean BCVA compared to the MSICS-Trab group, though not statistically significant. A higher proportion of patients in the PHACO-Trab group attained good visual outcomes, while fewer had moderate impairment. These findings are consistent with prior studies suggesting that phacoemulsification-based surgeries offer better visual rehabilitation due to less surgically induced astigmatism and smaller incisions [13, 14]. Furthermore, refractive predictability was superior in the PHACO-Trab group: approximately two-thirds of eyes were within ± 0.50 D of the target refraction compared to about 40% in the MSICS-Trab group, with notably lower surgically induced astigmatism. This enhanced accuracy is likely attributable to the smaller incision size, better wound stability, and more precise IOL centration in phacoemulsification procedures. Based on these findings, we recommend PHACO-Trab as the more suitable technique in patients where rapid and predictable refractive visual recovery is desired, particularly in those with bilateral disease, high functional demands, or where precise refractive outcomes are critical.

Intraocular pressure control

Both surgical approaches produced a substantial and sustained reduction in IOP by 24 weeks, with no significant difference between the groups. These results are in line with previous reports from sub-Saharan Africa and Asia, where combined cataract–trabeculectomy procedures were shown to achieve effective postoperative IOP control, regardless of whether phacoemulsification or MSICS was employed [12, 22]. Similar findings were observed in a Kenyan multicenter study, which reported comparable pressure-lowering outcomes between the two techniques [22]. Internationally, systematic reviews and meta-analyses have likewise confirmed that both phaco-trabeculectomy and MSICS-trabeculectomy effectively lower IOP, with the choice of technique influenced more by surgical setting, available technology, and patient profile than by efficacy [12, 13, 22]. Taken together, these data reinforce MSICS-Trab as a viable and cost-effective alternative where phacoemulsification facilities are limited, while confirming that both techniques remain reliable options for long-term IOP control.

Surgical success and failure

At 24 weeks, the proportion of eyes achieving complete surgical success was similar in both groups, with no significant difference between them. Likewise, the rate of surgical failure was comparable. These findings confirm the clinical utility of both procedures. Importantly, subgroup analysis revealed that eyes with hypotony accompanied by additional complications were far more likely to fail, whereas isolated hypotony was generally compatible with good outcomes. This underscores the importance of vigilant postoperative monitoring and prompt management of hypotony, as well as strategies to minimize intraoperative or postoperative complications.

Multivariate regression further demonstrated that baseline IOP ≥ 21 mmHg, worse visual field mean deviation, and postoperative complications were independent predictors of surgical failure. These findings align with previous reports: a Tanzanian cohort found that elevated preoperative IOP significantly increased trabeculectomy failure risk (HR 1.72) [27]; visual field severity has also been correlated with poorer surgical outcomes [28]; and early postoperative complications such as wound leaks have been linked to higher failure rates [29]. These results suggest that preoperative disease severity and the occurrence of postoperative complications may critically influence long-term surgical success.

Postoperative complications

Complication rates differed between the groups, with MSICS-Trab demonstrating a noticeably higher incidence of hypotony, posterior capsule opacification, and surgically induced astigmatism. In contrast, fibrinous uveitis and transient IOP elevation occurred at similar frequencies in both groups. The greater burden of refractive and anatomical complications in MSICS-Trab likely contributed to the relatively lower visual outcomes noted compared to Phaco-Trab. These observations are consistent with previous reports indicating that phacoemulsification is associated with a lower risk of significant astigmatism and secondary capsular changes, largely due to smaller incisions and more stable intraocular lens positioning [18, 19]. Although the scleral flap was closed with two 10 − 0 nylon sutures (one releasable) in both groups, the larger 6–7 mm MSICS cataract tunnel and greater tissue manipulation might have increased the risk of wound leak/over-filtration and thus contributed to the higher hypotony rate observed. Furthermore, the use of rigid PMMA intraocular lenses in the MSICS-Trab group, compared with foldable acrylic lenses in the Phaco-Trab group, may have predisposed to the higher rate of posterior capsule opacification observed, consistent with prior report that lens material and edge design influence PCO development [30].

Medication reduction

A substantial reduction in the need for antiglaucoma medications was observed in both groups over the study period. By 24 weeks, only a small proportion of eyes in either group remained on treatment, representing a marked decrease from baseline. In our opinion, this reduction is particularly meaningful for low-resource settings, where the long-term costs of topical therapy and challenges with adherence are concerns [31]. Both techniques, therefore, provide the dual benefit of effective IOP control and reduced dependence on medications, with slightly fewer MSICS-Trab patients requiring AGMs at the endpoint.

Factors influencing outcomes

Multivariate analysis identified high baseline IOP, poor visual field indices, and postoperative complications as independent predictors of surgical failure. These findings underscore the importance of thorough preoperative assessment, especially of functional damage and IOP level, as well as the need for meticulous intraoperative and postoperative care to prevent complications that may compromise surgical success. Similar associations between preoperative disease severity, postoperative complications, and surgical failure have been reported in African and international populations [27, 32, 33]. Given the high burden of cataract and glaucoma in low- and middle-income countries, particularly in sub-Saharan Africa, the results of this study have shown significant implications that support combined surgical intervention in resource-limited settings. The findings support alternative ophthalmic surgical option (MSICS-Trab) in localities where phacoemulsification may not be universally accessible.

Strengths and limitations

The follow-up duration of 24 weeks was adequate to assess early and intermediate postoperative outcomes but did not capture long-term IOP control, bleb survival, or visual field progression. A longer follow-up is planned to evaluate the sustainability of surgical success and assess late-onset complications.

Although outcome assessors were masked, surgeons and patients were not, which may introduce performance or observer bias. Interobserver agreement was established during the pilot phase (90% between registrars for IOP, VCDR, and gonioscopy; and 90% between nurses for visual acuity), but calibration details for the full study period and formal reproducibility across all assessors were not reported. The study was conducted at a single tertiary center, where surgical protocols and patient demographics may differ from other settings. We also did not conduct a pre-study assessment of inter-surgeon variability (e.g., calibration or run-in procedures).

Randomization was performed at the eye level; thus, some patients contributed both eyes, introducing intra-individual correlation that may affect independence of outcomes. Of the 200 randomized eyes, 151 eyes completed 24-week follow-up, with 49 eyes (≈ 24.5%) lost to follow-up. While the achieved sample size exceeded the requirement for detecting a 3 mmHg IOP difference, the study was underpowered to detect smaller IOP differences and secondary outcomes such as BCVA. Non-significant small differences (e.g., minor IOP or BCVA changes, near-identical success rates) should therefore be interpreted with caution. Larger multicenter studies with longer follow-up are needed to validate these findings.

Conclusion

Both phaco-trabeculectomy and MSICS-trabeculectomy demonstrated comparable short-term efficacy in improving visual outcomes, lowering IOP, and reducing antiglaucoma medication use in patients with coexisting cataract and primary open-angle glaucoma. PHACO-Trab offered advantages in terms of lower surgically induced astigmatism and faster visual rehabilitation, while MSICS-Trab remained a cost-effective alternative with slightly higher rates of early complications. Surgical choice should be guided by patient characteristics, surgeon expertise, and resource availability. Larger multicenter studies with longer follow-up are needed to validate these results, establish the durability of surgical success, and assess long-term effects on glaucoma progression and quality of life.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contributions

Conceptualization: MIM, NBG; Experiments: MIM, MOA, UI; Supervision: MOA, OTA; Analysis and interpretation of data: MIM, EJD, JDP; Writing the manuscript: EJD, MIM; Proofreading and editing: MIM, EJD, MOA.

Funding

None.

Data availability

The data included in this study is available upon reasonable request from the corresponding authors, Melchizedek Ignatius Munaje [munaj452@gmail.com] and Mayor Orezime Atima [atimamatha@yahoo.com].

Declarations

Ethical approval

This study involves human participants and was approved by the Human Research Ethics Committee of ECWA Eye Hospital (ECWA/HREC/004/2022). Written informed consent was obtained from all participants, and the study adhered to the principles of the Declaration of Helsinki (2013, Fortaleza, Brazil). The trial was registered on ClinicalTrials.gov (NCT06739343) on December 18, 2024.

Patient consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.