The central and peripheral corneal response to short-term hypoxia.

PURPOSE: To quantify the magnitude and recovery of central and limbal corneal oedema induced by short-term unilateral eyelid closure without contact lens wear. METHODS: The left eye of 10 adults with healthy corneas was patched using a folded eye pad for 30 min. High-resolution optical coherence tomography images (which captured the limbal and central corneal regions simultaneously) were obtained before patching, immediately after eye opening and again at 1, 2, 5, 6, 9, 10, 14 and 15 mins after eyelid opening. Oedema was measured from the limbus (scleral spur) to the central cornea (thinnest corneal location) along the horizontal meridian. RESULTS: A greater amount of limbal oedema was noted (mean [SD] 3.84 [1.79] %) compared to the central cornea (2.48 [0.61] %; p = 0.04) after 30 mins of unilateral eyelid closure. Both central and limbal corneal oedema recovered rapidly following eyelid opening, with no significant differences in the rate of corneal recovery between corneal locations (p = 0.90). CONCLUSIONS: Short-term unilateral eyelid closure resulted in ~55% more relative oedema in the limbal region compared to the central cornea. Rapid recovery of oedema and corneal overshoot (thinning beyond the baseline corneal thickness) was observed within 1-2 min of eyelid opening for both central and peripheral regions.

Post-Penetrating Keratoplasty Assessment of Endothelial Function With a Scleral Lens Challenge.

ABSTRACT: Patients who have undergone penetrating keratoplasty may have corneal edema because of endothelial cell dysfunction. Scleral lens wear may exacerbate edema, particularly if lens fit is suboptimal. Distinguishing between edema because of inherent endothelial cell dysfunction and swelling because of scleral lens-related hypoxia can be challenging. It is necessary, however, to identify the most likely cause of increased corneal thickness to determine whether the patient simply needs refitting for a different lens design or needs additional surgical intervention. This case report describes the utility of corneal tomographic imaging before and after scleral lens wear both to estimate endothelial cell function and to direct decisions when designing a scleral lens for a post-transplant eye.

Continuous Corneal Endothelial Damage by Chlorhexidine Alcohol Used for Disinfection in Nonophthalmic Surgery.

PURPOSE: To report a case of corneal endothelial damage caused by alcohol-containing chlorhexidine gluconate (CG-A) and its progression over time. METHODS: This was a case report. RESULTS: A 22-year-old man underwent neurosurgery under general anesthesia. CG-A (1%) was used for disinfection after the application of corneal protection tape. Postoperatively, the patient presented with hyperemia and swelling of the left conjunctiva and was referred to our department. Initial examination revealed left corneal epithelial erosion and corneal edema, which improved on postoperative day 14. The corneal endothelial cell density (ECD) was 3,345 cells/mm 2 on day 14, decreased rapidly to 2,090 cells/mm 2 on day 42, and slowly reduced to 1,122 cells/mm 2 on day 168. Thereafter, no decrease in ECD was observed. CONCLUSIONS: CG formulations can lead to a persistent decrease in ECD over several months, even after improvement of acute corneal edema.

The predictive value of anterior segment optical coherence tomography for postoperative corneal edema in cataract patients.

OBJECTIVE: To evaluate the predictive value of anterior segment optical coherence tomography (AS-OCT) for postoperative corneal edema in cataract patients. METHODS: A retrospective cohort study of 144 cataract patients from December 2020 to December 2021 was conducted. Patients were divided into edema eyes (84 cases) and observation (60 cases) group based on postoperative corneal edema occurrence. Relevant indicators were compared between groups. Logistic regression identified risk factors for postoperative corneal edema. Receiver operating characteristic curves evaluated the predictive value. RESULTS: The edema eyes group had significantly higher postoperative central corneal thickness (CCT) and lower postoperative endothelial cell density (ECD) than the observation group (P < 0.05). The edema eyes group also had significantly lower preoperative ECD, anterior chamber depth (ACD), anterior chamber angle (ACA), and preoperative lens position (LP) than the observation group (P < 0.05). Logistic regression analysis showed that preoperative ECD, ACD, ACA, and LP were independent risk factors for postoperative corneal edema (P < 0.05), all of which also showed good predictive value for postoperative corneal edema, with areas under the curve (AUCs) of 0.854, 0.812, 0.791, and 0.778, respectively, under the ROC curve analysis. CONCLUSION: AS-OCT can provide useful information for predicting postoperative corneal edema in cataract patients. Preoperative ECD, preoperative ACD, preoperative ACA, and preoperative LP are important parameters that can be measured by AS-OCT and used as risk factors for postoperative corneal edema.

Analysis of influencing factors of corneal edema after phacoemulsification for diabetic cataract.

The paper aimed to explore the influence factors of corneal edema after phacoemulsification for diabetic cataracts. For this aim, 80 patients (80 eyes) with senile cataracts who underwent phacoemulsification implantation in our hospital from August 2021 to January 2022 were included in this study, including 39 males (48.75%) and 41 females (51.25%), with an average age of 70.35±5.22 years. The OCT system during ophthalmology was used to capture corneal OCT images in the center of the cornea in real time before the phacoemulsification (the phacoemulsification probe just entered the anterior chamber after the balanced saline left the separated nucleus), at the end of phacoemulsification (when the phacoemulsification ultrasound probe was still in the anterior chamber and the perfusion pressure did not change compared with that in the previous step), at the end of perfusion aspiration (after the perfusion aspiration probe left the anterior chamber), and after surgery (after the watertight incision is closed). The corneal thickness was measured at each time point using Photoshop software. AL, curvature and ACD were measured using IOL-Master bio-measurement technology, and ACD referred to the distance between the front surface of the cornea and the front surface of the lens. Endothelial cell density was measured using CIM-530 non-contact mirror microscope. A handheld rebound tonometer was used to measure intraocular pressure and optical coherence tomography was used to assess the macular area of the fundus. Fundus photography was performed with a non-diffuse fundus camera. The results indicated that the preoperative corneal thickness was 514.35±29.62 µm, and the average corneal thickness at the end of the operation was 535.26±30.29µm, which was increased by 20.91±1.67 µm compared with that before operation (P<0.05), and the increase rate of corneal thickness was 4.07%. The corneal thickness of patients tended to increase with the increase in operation time and intraocular operation time (P<0.05). The distribution of corneal edema-related features showed that 42.50% of patients had persistent edema at the time of cataract surgery. The median onset time of corneal edema in the remaining patients was 5.44 years (1.96-21.35 years for 90% CR). The higher the nuclear hardness, the more severe the cataract, and the higher APT, EPT, APE, and TST (P<0.05). The older the patient, the higher the grade of cataract nucleus, and the higher EPT, APE, and TST, the greater the intraoperative corneal thickening (P<0.05). The higher the maximum area of endothelial cells, the greater the intraoperative corneal thickness increase, the lower the corneal endothelial cell density and the greater the intraoperative corneal thickness increase (P<0.05). It was concluded that postoperative corneal edema in phacoemulsification surgery for diabetic cataracts is closely related to intraocular perfusion pressure, nuclear hardness of lens, the density of corneal endothelial cells, the energy of phacoemulsification and duration.

Case Report: Role of Anterior Segment Optical Coherence Tomography for Managing Failed Endothelial Keratoplasty Graft.

SIGNIFICANCE: Some patients show poor visual outcomes after Descemet stripping automated endothelial keratoplasty. In such cases, secondary Descemet membrane endothelial keratoplasty can be performed to achieve complete visual recovery. Anterior segment optical coherence tomography (AS-OCT) is a valuable tool for the follow-up of posterior lamellar keratoplasty outcomes and complications. PURPOSE: This study aimed to report the clinical outcome of secondary Descemet membrane endothelial keratoplasty for managing poor visual results in a patient with graft failure after a previous Descemet stripping automated endothelial keratoplasty, highlighting the importance of AS-OCT in the follow-up of endothelial keratoplasty. CASE REPORT: A 38-year-old woman with high myopia underwent Descemet stripping automated endothelial keratoplasty for bullous keratopathy after explantation of an angle-supported phakic intraocular lens. Two years after keratoplasty, the patient experienced poor visual acuity (counting fingers), and significant corneal edema was observed on clinical examination hindering visualization of the anterior chamber structures. Anterior segment optical coherence tomography showed a failed and thickened graft adhering well to the recipient cornea in an anterior chamber without other comorbidities. Therefore, the graft was removed and replaced with a Descemet membrane endothelial keratoplasty graft without any complications. One year later, the clinical outcome was evaluated by comparing the pre-operative and post-operative best-corrected visual acuity, biomicroscopy findings, endothelial cell density, and corneal central thickness. CONCLUSIONS: Anterior segment optical coherence tomography is an important tool when deciding on the surgical technique to be applied and for the post-surgical monitoring of endothelial corneal grafts. This case demonstrates the successful management of Descemet stripping automated endothelial keratoplasty graft failure with Descemet membrane endothelial keratoplasty graft, highlighting the importance of AS-OCT in detecting complications such as graft dislocation and primary graft failure. In addition, corneal thickness measured using AS-OCT serves as a critical predictor of graft failure, as observed in this case.

Corneal oedema during reverse piggyback scleral lens wear.

PURPOSE: One clinical approach to address poor front surface wettability during scleral lens wear is the use of a "reverse piggyback" system (a soft contact lens applied to the anterior surface of a scleral lens). The aim of this study was to compare the magnitude of corneal oedema induced following short-term reverse piggyback scleral lens wear and standard scleral lens wear. METHODS: Ten young (mean age 22 ± 6 years) healthy participants with normal corneas were recruited. On separate days, central corneal thickness and fluid reservoir thickness were measured using optical coherence tomography before and after 90 min of standard scleral lens wear (Kerectasia Alignment Tangent Torus diagnostic lenses, hexafocon A, Dk 100 × 10-11 (cm2 /s)(ml O2 /ml × mmHg), Capricornia Contact Lenses, capcl.com.au) and reverse piggyback scleral lens wear (the same scleral lens with a Dailies Total 1®, delefilcon A, Dk 140 × 10-11 (cm2 /s)(ml O2 /ml × mmHg), Alcon, alcon.com, applied to the anterior scleral lens surface). RESULTS: After correcting for small variations in the initial central fluid reservoir thickness, central corneal oedema was similar between the reverse piggyback (2.32 ± 1.15%) and standard scleral lens conditions (2.02 ± 0.76%; p = 0.45). CONCLUSIONS: Following 90 min of lens wear, the highly oxygen-permeable reverse piggyback system did not induce a clinically or statistically greater magnitude of central corneal oedema compared with standard scleral lens wear in young adults with healthy corneas. This approach may be suitable to address poor front surface scleral lens wettability or to correct residual refractive error during diagnostic scleral lens fitting.

Corneal Hydrops - Aetiology and Advanced Therapeutic Strategies. / Der korneale Hydrops ­ Ursachen und moderne Therapieansätze.

Acute hydrops refers to sudden corneal edema caused by rupture of Descemet's membrane (DM) - often in progressive keratectasia. It leads to a sudden decrease in visual acuity, pain, and foreign body sensation as well as an increased glare sensation. Acute hydrops usually heals with scarring within months, but complications such as corneal perforation, infectious keratitis, and corneal vascularization may occur. The prevalence in keratoconus patients is 2.6 to 2.8%. Risk factors include keratoconjunctivitis vernalis, atopic dermatitis, high keratometry, male gender, and eye rubbing. Keratoplasty should be avoided in the acute phase. The prognosis of the graft is reduced, and after scar healing of the hydrops, wearing contact lenses or glasses may be possible again. Conservative therapy alone with lubricants and hyperosmolar eye drops, prophylactic antibiotic eye drops to prevent superinfection, and topical steroids was long considered the only possible form of treatment. However, healing under conservative therapy takes an average of over 100 days. In the meantime, there are different surgical strategies that rapidly shorten the healing and thus the recovery phase of the patients to a few days. If the DM is detached without tension, a simple injection of gas into the anterior chamber can already lead to reattachment and thus to almost immediate deswelling of the cornea. If the DM is under tension, predescemetal sutures combined with a gas injection into the anterior chamber can flatten the cornea and reattach the DM. Mini-Descemet membrane endothelial keratoplasty (mini-DMEK) allows for sutureless closure of the DM defect by transplantation of a small (< 5 mm) graft. In cases of particularly large DM tears and very pronounced hydrops, suture loosening and relapse may occur after the placement of predescemetal sutures. Mini-DMEK can then lead to permanent healing, but in contrast to simple corneal sutures, it is usually performed under general anesthesia and by aid of intraoperative optical coherence tomography. The very good results with regard to the rapid healing prove that surgical therapy makes sense in the vast majority of patients with acute hydrops and should be initiated quickly.

Refractive changes and visual quality in patients with corneal edema after cataract surgery.

BACKGROUND: To assess visual quality and stabilization of refractive changes in corneal edema patients after cataract surgery, using visual acuity (VA) and contrast sensitivity measurements. METHODS: Sixty-one eyes were analysed, twenty-three with and thirty-eight without corneal edema. Uncorrected and corrected distance VA (UDVA and CDVA) were determined with an EDTRS chart, the contrast sensitivity function (CSF) under photopic and mesopic illumination conditions with a CVS-1000e chart, clinical refraction, and corneal topography. Measurements were taken preoperatively, 1-2 days, 1 and 3-months after surgery. Clinical refraction was converted to vector notation (M, J0, J45) and SPSS v26.0 was used for data analysis. RESULTS: An improvement of VA was observed through the postoperative period; changes between visits were significant for CDVA in both groups and for UDVA in the edema sample. Significant astigmatic changes (J0,J45) between visits were not observed, but M values showed a hyperopic tendency in the edema group and a myopic shift in the control group that did not change between visits, with statistically significant differences between groups. Controls had significantly better contrast sensitivity at high spatial frequencies. Under mesopic conditions, global contrast sensitivity losses were observed in the edema group, which improved between visits in the middle frequency range. CONCLUSION: Corneal edema patients had a significant reduction of CDVA, and frequency-selective sensitivity losses that evidence a visual quality loss. Clinical refraction may improve visual quality, but in edema patients these losses are related to corneal changes, which did not change at three months after surgery.

Case Report: Acute Corneal Hydrops despite Accelerated Transepithelial Corneal Cross-linking.

SIGNIFICANCE: Corneal cross-linking is a well-established treatment to reduce or halt the progression of keratoconus. This case demonstrates that acute corneal hydrops may develop several years after corneal cross-linking even despite apparent treatment effect with corneal flattening, and patients should be monitored accordingly. PURPOSE: This study aimed to describe a case of continued progression in the form of corneal hydrops despite prior corneal cross-linking and evidence of treatment effect. CASE REPORT: A 19-year-old woman underwent bilateral accelerated transepithelial corneal cross-linking for progressive keratoconus. At 2 years after the procedure, significant flattening of the central cornea of >3 D was measured in the left eye, indicating a significant treatment response, although continued thinning was noted on tomography. At 3.5 years after the procedure, this eye developed acute corneal hydrops with subsequent corneal scarring necessitating corneal transplantation. CONCLUSIONS: Patients should continue to be monitored for several years after corneal cross-linking, and retreatment should be considered if there is progressive corneal thinning.

Corneal oedema during open-eye fenestrated scleral lens wear.

INTRODUCTION: Studies examining the effect of fenestrating soft and corneal rigid contact lenses upon corneal oedema have yielded conflicting results. Although often utilised in clinical practice, no studies have quantified the effect of fenestrating a scleral contact lens upon corneal oedema. Therefore, the aim of this experiment was to examine the effect of incorporating a single peripheral fenestration on central corneal oedema during short-term open-eye scleral lens wear, while controlling for potential confounding variables. METHODS: Nine participants (mean age 30 years) with normal corneas wore a fenestrated (1 × 0.3 mm limbal fenestration) and non-fenestrated scleral lens (both lenses manufactured using a material Dk of 141 × 10-11  cm3 O2 (cm)/[(sec.)(cm2 )(mmHg)]) under open-eye conditions on separate days. Scleral lens thickness profiles were measured using a high-resolution optical coherence tomographer (OCT). Epithelial, stromal and total central corneal oedema were also measured using the OCT immediately after lens application and following 90 min of wear, prior to lens removal. RESULTS: After adjusting for differences in initial central fluid reservoir thickness and scleral lens thickness between the two lens conditions, the mean (standard error) total corrected central corneal oedema was 0.50 (0.36)% for the fenestrated lens and 0.62 (0.16)% for the non-fenestrated lens. This small difference was not statistically significant (t8  = 2.31, p = 0.81) and represents a 19% relative reduction in central corneal oedema. Similarly, epithelial (t8  = 2.31, p = 0.82) and stromal (t8  = 2.31, p = 0.92) corneal oedema were not significantly different following the fenestrated and non-fenestrated wearing conditions. CONCLUSION: Central corneal oedema in healthy corneas was comparable between fenestrated and non-fenestrated high Dk scleral lenses under short-term open-eye conditions when controlling for lens oxygen transmissibility and initial central fluid reservoir thickness.

Scleral Lens Thickness and Corneal Edema Under Open Eye Conditions.

PURPOSE: To examine the relationship between lens thickness and central corneal edema during short-term open-eye scleral lens wear, and to compare these empirical edema measurements with theoretical modelling. METHODS: Nine participants (mean age 30 years) with normal corneas wore scleral lenses {Dk 141×10-11 cm3 O2 [cm]/([sec] [cm2] [mm Hg])} under open-eye conditions on separate days with nominal center thicknesses of 150, 300, 600, and 1,200 µm. Epithelial, stromal, and total corneal edema were measured using high-resolution optical coherence tomography immediately after lens application and after 90 min of wear, before lens removal. RESULTS: Central corneal edema was primarily stromal in nature and increased with increasing central lens thickness. The mean±standard error total corneal edema was 1.14±0.22%, 1.36±0.26%, 1.74±0.30%, and 2.13±0.24% for the 150, 300, 600, and 1,200 µm lenses, respectively. A significant difference in stromal and total corneal edema was observed between the 1,200 and 150 µm thickness lenses only (both P<0.05). Theoretical modelling overestimated the magnitude of central corneal edema and the influence of central lens thickness when the scleral lens Dk/t was less than 20. CONCLUSION: Scleral lens-induced central corneal edema during short-term open-eye lens wear increases with increasing central lens thickness. Theoretical models overestimated the effect of increasing scleral lens thickness upon central corneal edema for higher lens thickness values (lens Dk/t<20) when controlling for initial central fluid reservoir thickness.

Scleral Lens Thickness and Corneal Edema Under Closed Eye Conditions.

OBJECTIVES: To examine the relationship between central lens thickness and central corneal edema during short-term closed eye scleral lens wear. METHODS: Nine participants (mean age 30 years) with normal corneas wore scleral lenses (Dk 141) under closed eye conditions on separate days with nominal center thicknesses of 150, 300, 600, and 1,200 µm. Epithelial, stromal, and total corneal edema were measured using high-resolution optical coherence tomography immediately after lens application and after 90 min of wear, before lens removal. Data were corrected for variations in initial fluid reservoir thickness and compared with predictions from theoretical modeling of overnight scleral lens wear. RESULTS: Scleral lens-induced central corneal edema was primarily stromal in nature. The mean±standard error of corrected total corneal edema was 4.31%±0.32%, 4.55%±0.42%, 4.92%±0.50%, and 4.83%±0.22% for the 150-, 300-, 600-, and 1,200-µm lenses, respectively. No significant differences in the corrected total corneal edema were observed across all thickness groups (P=0.20). Theoretical modeling of overnight scleral lens wear seemed to overestimate the relative increase in central corneal edema as a function of decreasing lens Dk/t for values lower than 25. CONCLUSION: The magnitude of scleral lens-induced central corneal edema during short-term closed eye lens wear did not vary significantly with increasing central lens thickness. Theoretical modeling of overnight closed eye scleral lens wear seems to overestimate the effect of increasing lens thickness.

Severe Corneal Edema Increases ECL From Grafts After DSAEK-Corneal Edema and ECL After DSAEK.

OBJECTIVES: To determine the relationship between the preoperative degree of corneal edema in the recipient and the endothelial cell density in grafts after Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This retrospective case series enrolled 111 eyes of 107 patients who underwent DSAEK. The preoperative and postoperative central corneal thickness (CCT) was measured by anterior-segment optical coherence tomography. Eyes were divided into three groups according to the preoperative recipient CCT: group A (mild edema): 550 µm

Corneal Oedema: Aetiology, Diagnostic Testing, and Treatment.

Corneal oedema results from an underlying pathology, which can be diverse in origin, and may be mechanical, dystrophic, or inflammatory, and affect any layer of the cornea. Diagnostic tools such as Scheimpflug imaging and anterior segment optical coherence tomography have standardised quantification of corneal oedema and have become important aids in clinical practice. Timely diagnosis and treatment are key to preventing irreversible damage to the corneal ultrastructure, such as anterior corneal fibrosis or endothelial cell damage. The oedema usually resolves quickly when the underlying cause has been addressed. Symptomatic treatment using hyperosmolar agents has failed to show any benefits in oedema resolution or improvement in visual acuity compared to placebo. In contrast, rho-associated protein kinase (ROCK) inhibitors offer a promising option for medical treatment in cases of endothelial dysfunction, but their safety and efficacy must be further validated in large scale clinical trials. Until then, endothelial or penetrating keratoplasties remain the mainstay treatment where structural changes to the cornea have occurred.

Diseases of the corneal endothelium.

The corneal endothelial monolayer and associated Descemet's membrane (DM) complex is a unique structure that plays an essential role in corneal function. Endothelial cells are neural crest derived cells that rest on a special extracellular matrix and play a major role in maintaining stromal hydration within a narrow physiologic range necessary for clear vision. A number of diseases affect the endothelial cells and DM complex and can impair corneal function and vision. This review addresses different human corneal endothelial diseases characterized by loss of endothelial function including: Fuchs endothelial corneal dystrophy (FECD), posterior polymorphous corneal dystrophy (PPCD), congenital hereditary endothelial dystrophy (CHED), bullous keratopathy, iridocorneal endothelial (ICE) syndrome, post-traumatic fibrous downgrowth, glaucoma and diabetes mellitus.

Scleral Lens-Induced Corneal Edema After Radial Keratotomy.

ABSTRACT: This case series examines the magnitude and regional variation in scleral lens-induced corneal edema in postradial keratotomy (RK) eyes. Scheimpflug imaging was used to measure corneal thickness across the central 6 mm before and after scleral lens wear in nine post-RK eyes (median age 64 years). Variations in corneal edema were examined as a function of distance from the corneal center (six 0.5-mm annuli) and from 0° to 360°. The median central corneal edema was 2.19% (interquartile range 1.03%-3.18%; P=0.02) and increased in magnitude and variability further from the central cornea (from 1.30% in the central 0-0.5 mm to 3.12% in the 2.5-3.0 mm midperiphery) (P=0.02). Scleral lens-induced corneal edema in post-RK eyes was greater in magnitude further from the corneal center and at the approximate location of corneal incisions.

Scleral Lens Visual Rehabilitation of Sequential Bilateral Corneal Hydrops With Post-LASIK Ectasia.

ABSTRACT: This case report describes a unique presentation of bilateral sequential acute corneal hydrops that manifested several years after laser in situ keratomileusis. Initial management included anterior chamber perfluoropropane gas injection and corneal suturing. Longer-term visual rehabilitation involved the use of scleral lenses which significantly reduced lower- and higher-order ocular aberrations.

Interface Fluid Syndrome 2 Decades After Laser-Assisted In situ Keratomileusis.

PURPOSE: To report a case of late-onset interface fluid syndrome (IFS) after laser-assisted in situ keratomileusis (LASIK). METHODS: A 94-year-old man was referred for evaluation because of persistent corneal edema 10 days after Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) for pseudophakic bullous keratopathy. RESULTS: After an uneventful DSAEK, the patient was treated with topical antibiotics and steroids. On presentation, a well positioned and oriented DSAEK graft was observed in the right eye, yet the cornea was edematous. Applanation tonometry was normal. Anterior-segment optical coherence tomography (AS-OCT) revealed a LASIK flap with a fluid cleft beneath it. Requery confirmed that LASIK was performed 21 years ago. Topical steroids were stopped, and after 2 weeks, the cornea was clear, and AS-OCT revealed complete resolution of the interface fluid. CONCLUSIONS: Even decades later, IFS should be considered as a source of corneal edema in patients after LASIK. Monitoring these patients with AS-OCT is recommended.

Development of a rabbit model of persistent hypotony without ciliary body injury.

In order to study the pathophysiological alterations of the ciliary body (CB) during persistent hypotony, it is necessary to develop an animal model without CB injury. In this study, we successfully established a modified model of persistent hypotony without CB injury in New Zealand rabbits. A 23-gauge pars plana vitrectomy (PPV) was performed and a trocar-formed fistula was allowed to remain in situ, to produce a continuous outflow of intraocular fluid. Both eyes underwent PPV with normal intraocular pressure (IOP); eyes with no surgical intervention were used as controls. The IOP was monitored and used to evaluate the reliability of the model. Secondary changes of hypotony were evaluated by slit-lamp biomicroscopy and B scans while morphological changes of the CB were observed by haematoxylin and eosin staining. The mean IOP in the hypotony groups were consistently lower than 6 mmHg. Furthermore, there were no significant differences in IOP between the PPV control group and normal eyes. Collectively, our data indicate that this model successfully simulates the secondary changes of hypotony, including a reduction in corneal size, corneal oedema, anterior chamber inflammation, morphological alterations of the CB, cataract, retinal detachment, and choroidal detachment. The morphological structure of the CB tissue changed dramatically after persistent hypotony, indicating that normal IOP may be required in order to maintain normal function in the CB. This model of persistent hypotony potentially represents a valuable tool for future studies aiming to investigate the pathophysiological mechanisms underlying CB dysfunction and other secondary changes that occur during hypotony.