Advancements in surgical modalities for corneal hydrops: A comprehensive review

Abstract

This review critically assesses the advancements in surgical modalities designed to manage corneal hydrops effectively. As corneal hydrops presents a complex challenge in ophthalmic care, there is a growing demand for innovative surgical approaches to enhance treatment efficacy. The review evaluates the latest scientific progress in surgical strategies, offering a thorough overview of the recent interventions. By examining contemporary techniques in detail, the review aims to provide valuable insights into the ever-evolving landscape of corneal hydrops management.

Methodology

A literature search was conducted using PubMed and Google Scholar databases to identify articles published during 1992–2025 using the keywords “acute corneal hydrops,” “keratoconus,” “surgical management,” and “corneal ectasia.” Articles were included if they fulfilled the following criteria: (a) described the clinical outcomes of surgical interventions for corneal hydrops; (b) were available in English; and (c) involved human participants. Case reports, case series, and clinical trials were included, while studies focusing solely on medical management or animal models were excluded. The reference lists of the included articles were also screened to identify additional relevant studies.

Introduction

In 1940, Rychener and Kirby were the first to use the term acute corneal hydrops (ACH) to describe the sudden event of aqueous humor entering the corneal tissue in keratectasia. ¹ This phenomenon has been reported to occur in 2.5%–3.0% of keratoconus (KCN) cases, 11.5% of pellucid marginal degeneration (PMD) cases, and 11% of keratoglobus (KG) cases over the past 10 years.^2,3 The development of ACH is extremely rare following post-refractive surgery ectasia.^4,5

Traditionally, ACH, marked by the abrupt rupture of the Descemet’s membrane (DM) and the compromise of endothelial barrier integrity, is considered a result of the gradual stretching of the corneal stroma in noninflammatory ectatic disorders.

This leads to exposure of the corneal stroma to aqueous fluid, which can result in the formation of clefts or cysts in the stroma. ⁶ Various risk factors have been found to be associated with ACH, including an earlier age of onset of ectasia, eye rubbing, reduced vision at presentation, keratoconjunctivitis, and Down syndrome. ⁷ The onset of ACH typically occurs between the ages of 12 and 66 years, with most cases manifesting during the second or third decade of life. Men may exhibit twice the risk of developing ACH compared with women.^7–9 Miyata et al. categorized the severity of ACH into three grades based on slit-lamp examination. Grade 1 refers to edema limited to a 3-mm diameter circular area around the center, while Grade 2 involves edema extending between 3 and 5 mm in diameter. Grade 3 is the most severe, with edema extending beyond 5 mm in diameter around the center. ⁹ Several studies have employed the same method for evaluating the severity of ACH. ⁸

Treatment options for ACH can be conservative, medical, or surgical. ¹⁰ Conservative and medical options include observation, topical lubrication, pressure patches, bandage contact lenses, topical steroids, antibiotics, hypertonic agents, cycloplegics, and topical hypotensive medications. ² These treatments provide symptomatic relief, reduce inflammation, and alleviate pain.

Although the conservative treatment of ACH typically takes 2–4 months from onset to resolution, this period may be prolonged for more than 8 months.^2,7 Patients are usually symptomatic during this period and complain of pain, photophobia, tearing, and low vision. The effectiveness of conservative treatment options has not been well-established^2,11; conservative treatment harbors the risk of several complications such as corneal neovascularization, keratitis, and perforation.^11–13 Resolution indicates the total improvement of epithelial and stromal edema along with the resultant scar with or without corneal neovascularization.

Several new off-label treatment options for ACH over the past 20 years include intracameral gas injection, compression sutures, endothelial keratoplasty, and deep anterior lamellar keratoplasty (DALK). ¹⁴ The rationale behind using these options in ACH is to accelerate resolution, curb patients’ symptoms, and limit the complications of ACH (e.g. corneal neovascularization). ¹⁴ However, these options were used to treat corneal hydrops not in acute settings but when ACH is unresponsive to conservative treatment and becomes progressive or chronic.^15,16 In this review, we comprehensively address the treatment options for ACH unresponsive to conservative measures.

Pneumodescemetopexy

Intracameral injections of various gases, such as air, sulfur hexafluoride (SF₆), perfluoropropane (C₃F₈), and perfluoroethane (C₂F₆), have been used to reduce corneal edema and accelerate recovery.^9,17–19 The gas injected into the eye’s anterior chamber (AC) acts as a tamponade, preventing the aqueous humor from penetrating the corneal stroma and promoting the reattachment of the DM. Additionally, the gas stretches the rolled edges of the ruptured DM, bringing them closer to facilitate the migration of endothelial cells over the exposed stroma. ¹⁰

The procedure typically involves constriction of the pupil before surgery to prevent injury to the lens. Subsequently, a small amount (0.1–0.2 mL) of aqueous humor is aspirated, and air or nonexpansile gas is injected into the AC, filling two-thirds of the chamber. A surgical peripheral iridectomy can be performed before gas injection to avoid gas-induced pupillary blockage. After the surgery, the patient should remain in the supine position as much as possible for 1–2 weeks. ²⁰

Intracameral air injection

In a 2002 case series focusing on ACH, Miyata et al. introduced the idea of using air to reattach the DM and prevent the passage of aqueous humor into the corneal stroma. ⁹ This retrospective comparative study evaluated the outcomes of intracameral air injection in 9 eyes with ACH associated with KCN and 21 KCN eyes treated conservatively. Despite the need for air re-injection in seven cases, with the number of injections ranging from one to four and an average duration of 3 days per injection, the study group demonstrated significantly quicker resolution of corneal edema (20.1 ± 9 versus 64.7 ± 34.6 days) and a shorter time to wear hard contact lenses (33.4 ± 5 vs. 128.9 ± 85 days) than the control group. Notably, no significant difference was observed in best spectacle corrected visual acuity (BSCVA) or contact lens corrected visual acuity (CCVA) between the two groups. Eventually the researchers proposed the use of SF₆ or C₃F₈ as a feasible alternative, thus eliminating the need for repeated injections in future studies. ⁹

Intracameral nonexpansile gas injection

Along with the idea of using long-acting gases, in 2005, Sii et al. ²¹ and Shah et al. ²² reported the first successful use of SF₆ and C₃F₈ in ACH secondary to KCN, respectively. The first report used nonexpansile SF₆ (at a concentration of 18%) and cyanoacrylate tissue adhesive to avoid the use of tectonic graft in a perforated cornea secondary to hydrops in a 14-year-old boy with Down syndrome. The second study reported using 0.2 cc of nonexpansile C₃F₈ (at a concentration of 14%) in a 14-year-old girl with Marfan syndrome. Subsequently, in another two case reports, SF₆ and C₃F₈ were used successfully by Vanathi et al. ²³ and Kaushal et al. ²⁴ for treating ACH due to PMD. Kiire and Srinivasan ¹⁸ also used C₂F₆ to treat ACH secondary to KG in both eyes of a 16-year-old patient with Down syndrome. Larger case series have evaluated the effects and complications of gas injection.

In another study, Panda et al. treated KCN and ACH and compared their outcomes with those of nine conservatively treated patients. In the treatment group, 6 of the 9 eyes needed re-injection of SF₆. The cornea became significantly thinner at week 3 of follow-up in the SF₆ group, reaching an average central corneal thickness of 0.694 mm within 12 weeks (0.991 mm in the control group). The treatment group also demonstrated statistically significantly better BSCVA at 12 weeks. ¹⁹

In another uncontrolled interventional case series, Sharma et al. used C₃F₈ to treat 14 patients with KCN and ACH; 92% of the cases responded to treatment within 6 weeks. They used ultrasound biomicroscopy (UBM) to evaluate the cases and observed a centripetal pattern of edema resolution. They also found a positive correlation between the size of the DM tear and edema in the mid-peripheral and peripheral parts of the cornea. Only one case with a substantial defect in the DM and intrastromal gas migration was unresponsive to therapy. They proposed such large tears in the DM as a negative predictive factor for success in cases of ACH. ⁶

In the largest trial in the literature, Basu et al. retrospectively compared the results of 14% C₃F₈ injection in 62 eyes with ACH (42 with KCN, 15 with PMD, and 5 with KG) with those of conservative therapy in 90 eyes with ACH (68 with KCN, 15 with PMD, and 7 with KG). ²⁵ Surgical (inferior or superior) iridectomy was used as part of the procedure in more than half of the cases following pupillary block in one-third of their initial cases. Patients were advised to lie in the supine position for 2 weeks. The procedure resulted in statistically significantly faster resolution in all cases in the injection group (78.7 ± 53.2 vs. 117.9 ± 68.2 days) as well as in the KCN subgroup; however, the difference was not statistically significant in PMD or KG cases. Ten cases in the injection group exhibited complications with an acute pupillary block on the first operative day, warranting gas decompression in seven cases. After performing a surgical iridectomy, researchers did not face this challenge. Other complications, such as corneal neovascularization, keratitis, and perforation, were observed in a higher proportion of eyes in the control group; however, no significant difference was observed.

Ting and Srinivasan reported using 14% C₂F₆ to treat ACH in eight patients with KCN. They proposed that the usage of C₂F₆ obviates the need for re-injections observed with the use of SF₆ gas as well as the risk of pupillary block observed with the use of C₃F₈ gas owing to intermediate longevity. The gas was absorbed within 6–8 days, leading to resolution of ACH in all patients. No patient needed more than one injection, and no complication was observed postoperatively. ²⁶

Complications and other concerns

SF₆ and C₃F₈ remain in the AC for 2 and 6 weeks, respectively. ²⁷ Despite the success of these preliminary reports, some studies have reported serious complications related to the intracameral use of gases. Aralikatti et al. reported the occurrence of Urrets–Zavalia syndrome (UZS) in the left eye of a 15-year-old boy following C₃F₈ injection, whose hydrops in the right eye was successfully treated with the same method. In this case, despite medical and surgical management of glaucoma with trabeculectomy, the patient exhibited limited visual outcome owing to advanced glaucoma. ²⁸ Vanathi et al. ²³ reported the occurrence of malignant glaucoma following intracameral C3F8 injection. Kiire and Srinivasan reported a case of bilateral ACH secondary to KG, whose one eye developed UZS after treatment. ¹⁸

Bersudsky et al. ²⁹ and Sharma et al. ³⁰ reported nonresolution of corneal hydrops in KCN following intrastromal migration of SF₆ and C₃F₈ gas bubbles, respectively, preventing edema resolution. Sharma et al. reported fish egg–like appearance of air in the stroma that did not move with eye movements as a sign of this complication. They proposed that a downward direction of the needle toward the iris plane and slow injection of gas may prevent this complication.

Although all types of gases in the AC have been proposed to inhibit endothelial cell growth in several in vitro studies, SF₆ is generally considered safe for the endothelium. Endothelial toxicity with the use of ocular gases has been reported in animal studies.^31,32 Nonetheless, all types of these gases, including air, SF₆, and C₃F₈, have been safely used not only to treat ACH but also to attach graft tissue in endothelial keratoplasty. Basu et al. compared the endothelial cell count after using C₃F₈ in a subgroup analysis with that of the control group and found no statistically significant difference. ²⁵

Thus, injecting gases intracamerally has certain advantages over injecting air. Gases can reduce the need for multiple injections and persist in the AC for an extended period until the endothelium is fully functional. However, certain disadvantages are associated with using gas, including raised intraocular pressure (IOP), pupillary block glaucoma, and uveitis. ²⁷

Intracameral gas injection with venting incisions

In ACH, the presence of stromal clefts has been reported in both anterior segment optical coherence tomography (AS-OCT) and UBM studies.^6,33 Venting incisions have been described as a part of DM detachment (DMD) surgery following cataract surgery and endothelial keratoplasty in the literature. ³⁴

Vajpayee et al. used a venting incision under AS-OCT guidance in addition to air injection in the AC to facilitate the egress of fluid from stromal clefts externally and enable the tamponade effect of the air internally. ³³ They used a 20-gauge micro-vitreoretinal blade to make three to four venting incisions and performed complete AC air fill for 10 min, followed by partial air fill to prevent pupillary block. The results were promising in this small series of five patients (four patients with KCN and one with KG), resulting in the resolution of edema in all cases within 2–3 weeks. Unlike Miyata et al., ⁹ in whom 7/9 eyes required repeat air injections, none of these cases required reinjection. They hypothesized that using venting incisions diminishes the burden of the endothelial cells to decrease the edema and may promote the formation of stromal scars to facilitate DM attachment.

Soleimani et al. used Tryptan Blue Dye (TBD) to localize the main stromal cleft, followed by one venting incision in the corneal tissue. After irrigation of TBD with balanced salt solution, they used 20% SF₆ as internal tamponade. The method was performed successfully in four patients, leading to the resolution of edema within less than 3 weeks. ³⁵

These findings show that venting incisions can be used in addition to gas injection for the repair of ACH through various methods, such as utilizing AS-OCT as a guide and TPD for locating the primary stromal cleft. The use of venting incisions is promising, with a 100% success rate, resolving edema in all cases within 2–3 weeks.

Combination of compression sutures and gas injection

Full-thickness sutures and gas injection

Upon damage, the DM has the potential to retract or coil. ³⁶ Initially, the DM needs to be reattached to the posterior stroma. Subsequently, the endothelium must migrate to the space between the torn edges of the DM and synthesize a new DM. The injection of certain substances, such as C₃F₈, can expedite the reattachment of the DM to the posterior stroma in the first stage; however, it has no effect on the second stage. Conversely, compression sutures can facilitate both initial reattachment and subsequent DM synthesis. This is likely achieved by bringing the DM and stroma into close proximity and ensuring that the torn edges of the membrane are closely aligned, allowing endothelial cells to promptly seal and cover the lesion.^37,38

In 2009, Rajaraman et al. introduced a series of compression sutures in combination with intraocular gas for addressing large intrastromal clefts and promoting re-apposition of the DM. ¹⁷ They used 2–5 full-thickness sutures with 10-0 nylon in 15 of the 17 cases, along with C₃F₈ gas injection, while the remaining two cases received C₃F₈ injection alone. The suture and gas injection group demonstrated a faster resolution of edema, with an average time of 8.87 ± 4.98 days, compared with 27.5 days in the gas injection alone group. The C₃F₈ bubble persisted in the AC for 10.75 ± 2.62 days; however, prophylactic use of oral acetazolamide and maintaining pupillary mydriasis prevented ocular hypertension, in contrast to the findings of another case series by Basu et al. ²⁵ Rajaraman et al. postulated that the emission of C₃F₈ gas through needle passage in the cornea may have a preventive effect on the IOP rise. They added the possible effect of venting incisions in the needle passage as a factor promoting ACH resolution. Three patients showed intrastromal gas migration, which resolved over time. On an average, suture removal was performed 3.7 weeks later.

Mohebbi et al. described the use of full-thickness sutures with 10-0 polypropylene on a straight needle and 20% SF₆ in 13 eyes with ACH (10 eyes with KCN, 2 with PMD, 1 with KG), leading to the resolution of edema 11.5 ± 6.5 days later. ³⁹ Notably, after suture removal within 3–4 postoperative weeks, two patients exhibited an increase in the corneal thickness, while others remained stable. Vohra et al. retrospectively reported full-thickness suture placement with intracameral gas injection of C₃F₈ in 43 eyes (38 eyes with KCN, 3 with PMD, 2 with KG) using the same method described by Rajaraman et al. ¹⁷ The number of sutures was 2–4 in this series. All patients’ pupils were dilated in the postoperative period, and they received prophylactic acetazolamide. The mean time to the disappearance of the gas bubble in the AC was 8.4 ± 1.7 days, and no patient needed re-injection of gas or developed ocular hypertension or any other complication. ACH resolved in the patients within 14.8 ± 3.5 days. ³⁷ When comparing large case series that employed the combination of full-thickness sutures and C₃F₈ injection, such as those by Rajaraman et al., ¹⁷ Vohra et al., ³⁷ and Biswas et al., ⁴⁰ with their counterparts that used only C₃F₈ injection (as seen in the study by Basu et al. ²⁵ ), a notable trend was observed. The resolution of ACH occurred much more rapidly in the three combination series, with timeframes of 8.87 ± 4.98, 14.8 ± 3.5, and 48 and 32 days, respectively, in contrast to a considerably longer period of 78.7 ± 53.2 days observed in the C₃F₈ injection alone group.

Although descemetopexy with gas tamponade can be considered a straightforward and efficient treatment method for expediting the healing process and enhancing visual acuity, in complex cases, such as those involving corneal clefts and chronic or sizable DMDs, the utilization of compressive sutures along with intracameral gas injection appears to be a more suitable approach. ³⁷ Suturing along with intracameral gas injection decreases the amount and number of gas fillings needed and reduces the complications associated with isoexpansile gases, such as pupillary block glaucoma, endothelium toxicity, and cataract formation.^17,37

Pre-DM sutures and gas injection

Chérif et al. used 3–7 pre-DM sutures with 10-0 nylon and air (except for one patient using C₃F₈) to treat ACH cases. ³⁸ With the use of pre-DM sutures, the corneal thickness started to decrease significantly from the first day after surgery to 1 month thereafter. Although they used air tamponade in six of the seven cases, no patient needed air re-injection in this series, in contrast to the study by Rajaraman et al. ¹⁷ They proposed that even without full-thickness sutures, an approximation of the Dua layer (thin acellular structure bordering the DM and stroma) should be sufficient to restore endothelial function with similar efficacy. The pathology of one of the patients’ corneal tissue in this series after transplant demonstrated very good apposition of the DM. Liu et al. conducted a study comprising eight patients, each experiencing ACH due to KCN in a single eye. ⁴¹ The patients were divided into two groups: four were randomly assigned to receive full-thickness sutures combined with intracameral air injection (FTS-AI), while the other four received pre-DM sutures combined with intracameral air injection (PDS-AI). Both groups experienced a reduction in the maximum corneal thickness of the scarred area and improvements in best corrected visual acuity (BCVA) within 1 week and 3 months after the surgery, respectively. The study revealed that the average time for resolution of corneal edema following FTS-AI was significantly lower than that following PDS-AI (11 ± 1.15 vs. 15 ± 1.41 days, p = 0.005). Notably, no significant differences were observed in the mean maximum corneal thickness and BCVA outcomes between the two groups at the 3-month follow-up. Jain et al. reported a novel surgical technique of partial-thickness compression sutures without descemetopexy with air or gas injection in two patients with KCN. ⁴² Compression sutures were passed through the stroma without contacting the DM. Edema resolution was noted intraoperatively and markedly reduced within the first week. In both cases, vision at presentation was counting fingers at less than one foot, which improved to 20/60 and 20/50 at the last visit, respectively.

Triple technique (compression sutures with gas injection and venting incision)

Siebelmann et al. described the triple technique for treating ACH, which involves the combination of microscope-integrated OCT (MI-OCT) to monitor the placement of venting incisions, pre-DM 10-0 nylon sutures, and injection of SF₆ in two cases. ⁴³ The defect in the DM of these two cases was relatively small. According to this study, the first case had a preoperative central corneal thickness of 866 µm and a DMD of 1070 µm. Following surgery, the central corneal thickness decreased to 649 µm on the first day, and the DMD reduced to 370 µm. Over the next 6 months, the detachment size decreased further to 240 µm, and the central corneal thickness was reduced to 483 µm. The second case involved a 41-year-old patient who had ACH for 2 weeks in the left eye. The BCVA was hand motion, and the preoperative central corneal thickness was 948 µm. After the surgery, the visual acuity improved to finger counting on the first day and 20/60 on the third day. A significant reduction was observed in corneal edema, and the postoperative central corneal thickness was 445 µm on the first day. The authors recommended the use of endothelial keratoplasty for managing larger DM defects. ⁴³ Masatoshi et al. documented a unique case involving a post-laser-assisted in situ keratomileusis (LASIK) ACH, characterized by a persistent fluid-filled space between the corneal flap and stromal bed. ⁴⁴ Initially, they attempted primary air injection to address the issue, some of which penetrated into the space beneath the corneal flap. After 2 months, no discernible improvement was observed. In a subsequent surgical procedure, the medical team combined air injection with the drainage of fluid from the interface (by creating an incision in the corneal flap) and then suturing the flap securely to the underlying stroma. After 3 months, a notable reduction was observed in corneal edema, and the patient’s vision improved significantly, going from hand motion perception to 20/66 vision. Sayadi et al. reported two cases of severe ACH. ¹⁵ One of these cases involved a 62-year-old man who had developed post-LASIK ACH. During the treatment for this patient, 20% SF₆ gas was intracamerally injected, creating a bubble occupying 90% of the AC. Subsequently, a venting incision was made inferonasally through the LASIK flap to release the accumulated fluid. At the 3-week follow-up, notably, a Seidel test indicated a leakage at the venting incision. Despite ongoing medical treatments, by the end of the first postoperative month, the Seidel test still detected a minor leak, prompting the placement of a 10-0 nylon suture. During a follow-up clinic visit 1 week later, no signs of corneal leakage were observed. At 2.5-month post-surgery, the patient’s vision had stabilized, reaching a BCVA of 20/30 with the assistance of a pinhole.

Post-LASIK ACH, although uncommon, presents a more intricate challenge than other ACH scenarios. This complexity arises from the presence of the LASIK flap and the accumulation of fluid beneath it. The potential for air to enter the sub-flap space during air injection and the possibility of leakage from venting incisions further add to the complexity. Given these considerations, it appears that employing the triple technique, which combines venting incision, sutures, and gas injection, is a more dependable surgical approach for addressing post-LASIK ACH, as opposed to relying solely on air injection. Future studies that compare various surgical strategies in such patients may yield improved approaches and insights into the optimal management of this condition.

Compression sutures

Subudhi et al. presented the first case of using full-thickness corneal sutures without gas injection, which resulted in the clearance of corneal edema within 28 days. ⁴⁵ They postulated that this technique is valid when intraocular gas injection is not feasible. García-Albisua et al. evaluated the effectiveness of this technique in a retrospective case series of 17 KCN cases. They placed 3–17 full-thickness nylon sutures based on the severity of hydrops. ¹³ Notably, three patients exhibited positive Seidel test results on the first postoperative day; they all responded to bandage contact lenses until the first postoperative week. The corneal pachymetry reached from 1235 µm preoperatively to 830 µm and 502 µm 1 and 3 months postoperatively, respectively. One case of ACH recurred after suture removal and was successfully treated with re-suturing. Compared with combination techniques involving gas and suturing simultaneously, the resolution of ACH was slower (4 weeks); however, their technique was safe and effective. In fact, they stated that the resolution time in this series is comparable to that of the gas injection alone method. They hypothesized that sutures may approximate the torn edges of the ruptured DM.

In a five-case series in 2023, Ashena et al. also used full-thickness sutures alone, which resulted in significantly decreased corneal thickness and edema in all cases. ⁴⁶ Two of the five patients even reached pre-hydrops visual acuity, with the third patient dropping by one line. The researchers postulated that the use of sutures alone is a safe and effective alternative to using combined intracameral gas and sutures, thus eliminating the need for a peripheral iridotomy to avoid pupillary block as well as IOP spikes. They also argue that leaving gas in the AC for extended periods increases the risk of cataract development, which would be an especially detrimental risk in ACH procedures given the young population affected by ACH.

Jain et al. documented two cases of successful treatment for ACH without the need for descemetopexy. ⁴² These cases involved the use of 10-0 nylon compression sutures placed across the region of corneal edema, precisely at the junction where the edematous and clear corneal stromas met. Importantly, this procedure was conducted carefully to ensure that there was no contact with the DM, and the AC remained completely intact throughout the surgical process. Remarkably, immediate improvement in the edema was observed during the surgery itself. Furthermore, postoperatively, additional resolution of edema began as early as the first day after the procedure, with significant reduction observed within the first week. After 6 weeks, both patients exhibited corneal scars without any residual edema. Moreover, their vision, initially limited to counting fingers, had substantially improved to 20/60 and 20/50, respectively, at their most recent follow-up appointments. The researchers proposed that using partial-thickness sutures alone without intracameral gas injection, similar to the study by Chérif et al., ³⁸ reduces the risk of complications associated with entering the AC. Their cases also demonstrated a faster resolution time than that reported by Subudhi et al. ⁴⁵ (9 days as opposed to 4 weeks), and they further postulated that avoiding full-thickness sutures prevents suture tract leaks and decreases the chances of infection while still possessing the advantage of approximating the edges of the DM together. ⁴²

A recent study by Daza et al. used compression sutures for managing ACH. ⁴⁷ They placed full-thickness corneal sutures across the edematous area to provide mechanical compression, facilitating fluid egress and accelerating the resolution of corneal edema. The study reported a 76% reduction in corneal edema within 24 h, with near-complete resolution achieved in 98.6% of cases by day 18. They suggested that this technique was a safer and more effective alternative to gas injection, which is associated with risks such as elevated IOP, endothelial toxicity, and pupillary block. They concluded that compression sutures could reduce the need for more invasive procedures, such as corneal transplantation, in patients with severe hydrops.

Cauterization or thermokeratoplasty

In 2014, Li et al. treated 21 patients with ACH using a novel approach. ⁴⁸ They combined AC paracentesis with thermokeratoplasty (TKP), which involved cauterizing the edematous cornea to induce central corneal contraction and flatten the cone-shaped protrusion. Within 1 week, edema was absorbed, and the DM rupture and stromal clefts were resolved. Following this, all patients underwent modified DALK in the second week. The study indicated that TKP effectively reduced tension on the cornea’s outer surface, leading to central corneal contraction and cone flattening. This, along with decreased IOP, facilitated the closure of DM rupture and minimized further aqueous humor influx into the corneal stroma. This rapid resolution of edema and corneal stroma healing provided an early window for DALK treatment. The longer the wound takes to heal, the greater the fibroblast activation and the more severe the resulting scar. If the duration of DM rupture and corneal edema is longer than 2 weeks in patients with ACH, obvious intrastromal scarring might be formed. ⁴⁹ Thus, it is not feasible to consider DALK as the subsequent surgery. The accelerated resolution of corneal hydrops makes it possible to perform DALK in these eyes.

Another study conducted by Hao and Feng in 2022 used one-step TKP without AC paracentesis in 10 patients with severe ACH. ⁵⁰ The aim was to relieve intense pain and corneal edema as early as possible to provide more surgical options. Changes in the corneal curvature, thickness, size, and morphology of the DM breaks were observed before and after the surgery. Modified DALK was successfully used to treat eight patients. The graft transparency, visual acuity, and immunological rejection were evaluated for 6–12 months after TKP. At 3–6 weeks after surgery, the DM breaks and intrastromal ruptures were healed, and corneal edema had faded. Eight patients underwent DALK successfully and safely after TKP without corneal perforation. Central corneal opacity had faded or disappeared within 6 months, and the mean BCVA increased to 20/30 at 12 months following DALK. No patient experienced immune rejection. Long-term management of ACH using this method seems promising.

In a prospective randomized trial conducted by Zhao et al. in 2021, compression sutures combined with intracameral air injection (CSAI) were compared with TKP for ACH in patients with KCN. ⁵¹ The study involved 20 patients and 20 eyes monitored for 6 months. Both treatments showed that corneal edema resolved within 2 weeks, and the maximum thickness of corneal scars did not significantly vary between the two groups. However, at the 6-month follow-up, the CSAI group had better clinical outcomes with superior BCVA (0.52 vs. 0.96 LogMAR, p = 0.042), greater corneal endothelial cell density (2677.8 ± 326.7 vs 1955.3 ± 298.1 cells/mm², p < 0.001), and a flatter corneal curvature (mean keratometry value: 52.13 ± 4.92 vs. 63.51 ± 5.83 D, p < 0.001; maximum keratometry value: 65.21 ± 7.42 vs. 77.13 ± 12.01 D, p = 0.016) than the TKP group. The study found that both treatments effectively resolved ACH in KCN; however, CSAI demonstrated better clinical outcomes.

Platelet-rich plasma injection

In a case report in 2019, Alio et al. discussed the successful treatment of ACH using eye platelet-rich plasma (E-PRP) of a 36-year-old woman with Down syndrome. ⁵² Despite previous attempts at medical treatment and intracameral SF₆ injection, the patient did not show improvement. Overall, 0.3 mL of sterile E-PRP was injected into the AC to address this issue. The patient experienced clinical and anatomical improvement from the first postoperative day, with corneal edema resolving within 1 week. The only side effect noted was an early transient moderate peak in the IOP (28 mmHg). Anterior segment OCT revealed significant normalization in corneal morphology, with the intracorneal cystic space completely disappearing, the DM rupture closing, and DM reattaching. The patient remained stable during the 6-month follow-up period. The posterior surface of the cornea was filled and covered with platelet-rich plasma, which acted as a mechanical barrier, similar to air and gas. This creates a tamponade effect that stops the aqueous humor from moving into the stroma. Additionally, the plasma contained various platelet-derived growth factors crucial for cell migration, differentiation, and proliferation. According to their findings, the use of intraocular E-PRP is considered an effective treatment option for managing corneal hydrops when traditional methods fail. This case was the first documented instance of using E-PRP in resolving DM rupture during an ACH episode.

Corneal transplantation

Corneal transplantation may be required at a relatively young age in approximately 12%–20% of patients with KC. ⁵³ In a retrospective study conducted by Meyer et al., ⁵⁴ the results of penetrating keratoplasty (PKP) were compared between KCN patients with a history of ACH and those without. The study found that the rate of corneal neovascularization was significantly higher in eyes with a history of ACH (44%) than in those without (7.6%). Additionally, neovascularization was identified as a risk factor for episodes of acute endothelial rejection during follow-up. The different keratoplasty procedures are explained below.

Endothelial keratoplasty

Descemet stripping endothelial keratoplasty (DSEK)

Some cases of ACH that are unresponsive to conservative treatment or show progressive worsening may be attributed to a larger tear in the DM or the nature of the underlying cause. In these cases, clinicians may proceed to reconstruct the endothelium via endothelial keratoplasty.

The first case of ACH treated with Descemet stripping automated endothelial keratoplasty (DSAEK) was reported by Gorovoy et al. in 2012. ⁵⁵ They reported the case of a 25-year-old patient with osteogenesis imperfecta presenting with atypical KCN and ACH. As the taut DM was unresponsive to gas injection, the surgeon treated him with DSAEK successfully. Kolomeyer and Chu successfully treated a case of KG and megalocornea with chronic hydrops using DSAEK. ⁵⁶ They avoided intracameral gas injection because it seemed futile in the presence of inferior DMD. Sharma and Fernandes successfully performed early DSAEK because of the visual needs of their mono-ocular KG patient who presented with severe ACH. ⁵⁷ They reported a patient with bilateral KG and adherent leukoma in both eyes and an ACH in the left eye caused by DMD. The extensive DM tear and severe ectasia posed challenges for air descemetopexy. Due to the patient’s monocular condition, early DSAEK was recommended to provide structural support for the thin cornea and ensure swift visual recovery. To prevent corneal tearing, a 7.5-mm diameter lenticule was inserted through a scleral incision using a Sheet’s glide. However, the lenticule decentered superiorly due to the presence of an inferior adherent leukoma. Palioura et al. documented a case of ACH in a patient with KG. ⁵⁸ Their initial attempt to approximate the edges of the Descemet tear via intracameral air injection was unsuccessful, leading to continued peripheral progression of the tear. To address excessive localized edema, they opted for an endothelial keratoplasty button with anchoring sutures placed over the Descemet tear. One month post-surgery, the edema had resolved, and 1 year later, the tear remained sealed. The patient’s visual acuity significantly improved, progressing from counting fingers at 1 foot to 20/100. Restoring the posterior corneal surface in cases of KG-induced hydrops can be accomplished through endothelial keratoplasty performed over the Descemet tear. Preventing the progression of a central Descemet tear is essential to circumvent the need for a large-diameter PKP graft and its potential complications, particularly in a young patient with a background of bilateral corneal hydrops. ⁵⁸ Blitzer et al. described the uneventful management of two hydrops cases associated with KCN and unresponsive to medical therapy using DSAEK. ⁵⁹ Turnbull et al. reported a case of PMD and ACH unresponsive to 6 weeks of medical therapy, which was managed successfully using non-DSEK with a manually dissected semicircular donor lenticule (hemi-nDSEK). ⁶⁰ The main reason for choosing this procedure was the impending perforation of the eye in the periphery with a history of perforation of the other eye after hydrops.

Descemet membrane endothelial keratoplasty (DMEK)

Dr Tu was the first surgeon to introduce mini-DMEK in a 55-year-old patient with KCN who exhibited persistent corneal edema due to hydrops for 7 months. ¹⁶ The patient was neither responsive to medical therapy nor a good candidate for gas injection. A 5-mm DMEK graft with the injection of 20% SF₆ was performed, successfully restoring vision and alleviating the patient’s pain.

In an uncontrolled trial involving three patients presenting with ACH, Siebelmann et al. used MI-OCT to ensure graft attachment during surgery and adjusted the DMEK graft size in relation to the size of the defect in the DM of the host. Although the operations were not straightforward (one patient needed re-DMEK, and two had partial graft detachment 1 week after surgery), all patients demonstrated a good outcome, experiencing vision gain and resolution of corneal edema. ⁴³

Performing a DMEK surgery in the deep AC with poor visualization due to edema can be challenging, particularly with respect to the positioning and orientation of the graft. To minimize the damage to normal host endothelium, surgeons often use a small graft, typically less than 5 mm in size. This approach also reduces the significance of the graft orientation as the normal host endothelium can easily repopulate the DM, even if the graft is accidentally inverted.

Subsequently, the same team compared mini-DMEK with pre-descemetal sutures in 16 young patients with acute hydrops (a mean of 10 days from onset) using the same technique. They found both methods successful and found no difference between the two methods in restoring vision or decreasing edema. They recommended mini-DMEK for these patients, especially those with a larger tear in the DM. ⁶¹ Recently, Maranhão et al. described the treatment of ACH secondary to KCN and ACH unresponsive to 1-month conservative therapy with an 8-mm DMEK graft. They mentioned poor visualization as a challenge in this surgery. ⁶²

DALK

Traditionally, anterior lamellar keratoplasty or PKP is not recommended in ACH cases. Even DALK in the scenario of resolved hydrops can be challenging, and several different techniques have been introduced to eliminate the scar tissue in this scenario and preserve the integrity of DM. Undertaking a DALK procedure after an ACH episode poses a significant challenge because of the complications arising from the scarring that typically occurs between DM and the posterior stroma following the acute episode. Nonetheless, the key advantage of DALK lies in its ability to preserve the host DM and endothelium, which leads to a lower risk of rejection compared with PKP. Nevertheless, there are reports of successful treatment of hydrops in the acute phase with DALK.

In 2014, Li et al. proposed the use of TKP and subsequent DALK in the ACH and KCN, which resulted in rapid resolution of ACH in all of their 21 patients. ⁴⁸ In this method, the IOP was lowered by draining 0.2 cc of aqueous humor and cauterization of the cornea performed in an area slightly larger than the edema. This resulted in edema resolution within 1–2 weeks. They defined a window period after TKP, which is approximately 2 weeks, as the most suitable time for proceeding to DALK surgery. This period occurs after the edema and clefts in the stroma are resolved by the use of TKP, but before the appearance of the scar tissue of resolved ACH. At the time of surgery, most patients had visible DM ruptures, leading to slight aqueous leakage in only three of them; however, no gross perforation occurred. In the 1-month follow-up, 7 patients had clear corneas, and the other 14 patients had visible DM rupture scars, which almost disappeared within 1 year. In 2019, Jacob et al. introduced pre-descemetic DALK as the primary treatment for ACH in a series of seven cases of KCN and used tuck-in lamellar keratoplasty for one patient with KG and another with PMD. This method included a combination of a small amount of air injection with a bevel-up needle in the periphery of the cornea and centripetal dissection of the cornea using a modified Melles technique. Finally, a small amount of stroma was left over from the DM tear, and full air was injected to maintain the AC. The method was successful in all cases without any serious complications. ⁸ In 2022, Liu et al. successfully treated seven cases of ACH using a two-step surgical procedure. ⁶³ The first stage was TKP-assisted epikeratophakia with intracameral sterile air injection to repair the DM, followed by a second stage of DALK using the same corneal graft after an average duration of 2.1 ± 0.7 months. In the 6-month follow-up after DALK, the corneal thicknesses significantly reduced and visual acuity improved. They were the first to publish this novel method and proposed that allowing time for the DM tear to heal using the first-stage TKP-assisted epikeratophakia provided more optimal conditions for the second-stage DALK. Additionally, the researchers proposed that the two-stage procedure minimizes the risk of postoperative endothelial rejection, indicating that DALK could be a useful method for treating ACH after the DM has been repaired and edema has subsided. Further research is warranted to determine whether DALK is a reliable and safe surgical method for treating ACH or whether it is advisable to wait until the corneal edema has fully subsided for 4–6 weeks before considering a DALK procedure.

Lamellar wedge resection

Petrelli et al. reported a case of a 47-year-old woman with a history of KCN who presented with acute corneal perforation due to ACH. ⁶⁴ The patient was treated with lamellar wedge resection after two unsuccessful applications of cyanoacrylate glue to seal the perforation. They proposed that the main advantage of this surgical approach is to avoid the need for performing corneal transplants and their intraoperative and postoperative complications. They stated that this method offers the advantage of corneal shape remodeling by removing protruding corneal tissue and improving the patient’s refractive power, with a possible reduction in post-op astigmatism and its rapid visual rehabilitation. They concluded that lamellar wedge resection could be considered an alternative to eccentric keratoplasty and avoids potential visual limitations.

Summary of outcomes

Multiple surgical approaches have been employed for the management of ACH, each with varying resolution times, complication profiles, and long-term visual outcomes. In general, techniques such as intracameral gas injection and compression sutures tend to accelerate resolution compared with conservative management, while combination procedures (e.g. sutures plus gas injection, venting incisions, or TKP) show further improvement in recovery times and anatomical outcomes. Table 1 summarizes the key findings from published studies included in this review.

Table 1.

Summary of the reported surgical interventions for acute corneal hydrops with corresponding resolution times and key clinical outcomes.

Surgical technique	Average resolution time	Key outcomes and notes
Intracameral air injection	20.1 ± 9 days (vs 64.7 ± 34.6 days conservative)	Faster edema resolution; similar final visual acuity to conservative treatment
Intracameral nonexpansile gas (SF6, C3F8)	6–12 weeks	Accelerated recovery; some risk of pupillary block and intrastromal gas migration
Gas injection + venting incisions	2–3 weeks	Complete edema resolution; no repeat injections needed in small case series
Compression sutures + gas injection	8–15 days	Faster edema resolution compared with gas alone; reduced need for repeat gas injection
Compression sutures alone	∼4 weeks (variable)	Safe alternative when gas injection is not feasible; slower than combination methods
Triple technique (sutures + gas + venting)	<3 weeks	Effective in complex cases including post-LASIK hydrops; good anatomical outcomes
Thermokeratoplasty ± anterior chamber paracentesis	1–2 weeks	Rapid pain relief and edema resolution; facilitates early keratoplasty
Platelet-rich plasma injection	∼1 week (case report)	Accelerated healing in refractory hydrops; transient IOP elevation reported
Corneal transplantation (PKP, DALK, DMEK, DSAEK)	Variable (weeks to months)	Reserved for severe or unresponsive cases; improved visual outcomes post-resolution

LASIK: laser-assisted in situ keratomileusis; IOP: intraocular pressure; PKP: penetrating keratoplasty; DALK: deep anterior lamellar keratoplasty; DMEK: Descemet membrane endothelial keratoplasty; DSAEK: Descemet stripping automated endothelial keratoplasty.

Conclusion

Individuals diagnosed with KCN and other corneal ectatic disorders may experience a rare but impactful condition known as ACH, particularly affecting young and otherwise healthy individuals. Several strategies have been employed to manage ACH, including conservative, medical, or surgical treatment, which mainly provide symptomatic relief until spontaneous recovery. Intracameral gas injection may be used to reduce the duration of corneal edema and minimize complications such as corneal neovascularization. In severe cases, compression sutures may complement intracameral gas injection to enhance healing. Cauterization, TKP, and platelet-rich plasma injection are alternative options for specific situations when patients are poor candidates for other procedures. Although these procedures offer several benefits, none can guarantee a definite improvement in the final visual acuity. In many cases, corneal transplantation is necessary for visual rehabilitation. PKP, DALK, DSAEK, DMEK, and lamellar wedge resection are all successful corneal transplantation procedures that have been used in different contexts of ACH. With the help of constantly evolving imaging modalities, our understanding and management of ACH are becoming more targeted and individualized.

Data availability

No new data were generated or analyzed in this study. Data sharing is not applicable to this article.

Declaration of conflicting interests

The authors declare that they have no conflicts of interest related to this work.