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.

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.

Amantadine therapy for Parkinson's Disease: In Vivo Confocal Microscopy corneal findings, case report and revision of literature.

BACKGROUND: To report a case of a patient showing bilateral corneal opacities after amantadine chronic treatment for Parkinson's Disease (PD) and corneal edema associated with intra-epithelial and -endothelial depositions. After amantadine discontinuation a complete clinical remission with only a partial ultrastructural corneal recovery was reported. CASE PRESENTATION: We describe a 78-year-old man with non-medical-responding bilateral corneal edema in treatment with systemic Amantadine for PD. In vivo confocal Microscopy (IVCM) analysis revealed hyperreflective particles at the epithelial level and expanded hyperreflective keratocyte and a disarrangement of stromal lamellae; endothelial cells showed hyperreflective intracellular inclusions in central and in peripheral areas with central polymegatism and pleomorphism. After 1 and 6 months the amantadine discontinuation, the absence of bilateral corneal edema and opacities were noted at the slit lamp examination, associated with the disappearance of epithelial and stromal abnormalities, but the persistence of endothelial hyperreflective deposits with a pleomorphism and polymegatism worsening at the IVCM exam. CONCLUSION: The evaluation of a patient's cornea 6 months after the discontinuation of systemic amantadine therapy showed a clinical complete remission, with a complete resolution of the bilateral corneal oedema. On the other hand, ultrastructurally, amantadine toxicity is a completely reversible phenomenon at the epithelial level; conversely IVCM showed persistent endothelial degradation.

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 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.

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.

Hyperosmolar Eye Drops for Diurnal Corneal Edema in Fuchs' Endothelial Dystrophy: A Double-Masked, Randomized Controlled Trial.

PURPOSE: The Eye Drops for Early Morning-Associated Swelling (EDEMAS) trial assessed the efficacy of hyperosmolar eye drops on corneal edema resolution. DESIGN: Double-masked, randomized controlled trial of hyperosmolar eye drops. PARTICIPANTS: Participants with Fuchs' dystrophy scheduled for Descemet membrane endothelial keratoplasty. METHODS: One eye was randomized to hyperosmolar eye drops (treatment); the fellow eye was randomized to artificial tears (placebo). After baseline examination in the afternoon, corneas were examined using Scheimpflug tomography after eye opening in the morning. Participants received eye drops twice. Imaging was repeated every 30 minutes up to 4 hours. MAIN OUTCOME MEASURES: Decrease in central corneal thickness 1 hour after eye opening (primary end point), corneal thickness, subjective visual function, glare, visual acuity, and adverse events (AEs) (secondary end points). RESULTS: A total of 68 participants received the allocated intervention (59 eyes received treatment; 55 eyes received placebo). All eyes had stromal edema; none had epithelial edema. Corneal thickness was 626 µm in the treatment arm and 622 µm in the placebo arm after eye opening, indicating an early morning edema compared with baseline of +21 µm and +24 µm, respectively. Decrease in corneal thickness after 1 hour was -10.5 µm in the treatment arm (95% confidence interval [CI], -12.8 to -8.2) and -11.2 µm (95% CI, -13.6 to -8.9) in the placebo arm (between-arm difference, 0.7 µm, 95% CI, -2.0 to 3.5; P = 0.59), indicating no clinically relevant effect of hyperosmolar eye drops on early morning corneal edema. Results were not compatible with a relevant treatment effect on corneal thickness, visual acuity, and glare over the entire course of the study. Increase in subjective visual function was less rapid in the treatment arm than in the placebo arm. Adverse events, most commonly burning after eye drop application, were more common with treatment (30 eyes) than placebo (1 eye; risk difference, 49 percentage points; 95% CI, 36-62). CONCLUSIONS: In this double-masked, randomized controlled trial, resolution of early morning stromal edema was not accelerated by hyperosmolar eye drops, which more frequently caused AEs. These results are not compatible with a clinically relevant effect of hyperosmolar eye drops and do not support their routine use.

Five-Year Follow-up of First 11 Patients Undergoing Injection of Cultured Corneal Endothelial Cells for Corneal Endothelial Failure.

PURPOSE: To report the safety and efficacy of a novel cell injection therapy using cultured human corneal endothelial cells (hCECs) for endothelial failure conditions via the report of the long-term 5-year postoperative clinical data from a first-in-humans clinical trial group. DESIGN: Prospective observational study. PARTICIPANTS: This study involved 11 eyes of 11 patients with pseudophakic endothelial failure conditions who underwent hCEC injection therapy between December 2013 and December 2014. METHODS: All patients underwent follow-up examinations at 1 week, 4 weeks, 12 weeks, and 24 weeks and 1 year, 2 years, 3 years, 4 years, and 5 years after surgery. Specific corneal endothelial cell parameters (i.e., corneal endothelial cell density [ECD], coefficient of variation of area, and percentage of hexagonal cells) and central corneal thickness, best-corrected visual acuity (BCVA) on a Landolt C eye chart, and intraocular pressure (IOP) were recorded. MAIN OUTCOME MEASURES: The primary outcome was the change in central ECD after cell injection therapy, and the secondary outcome was corneal thickness, BCVA, and IOP during the 5-year-postoperative follow-up period. RESULTS: At 5 years after surgery, normal corneal endothelial function was restored in 10 of the 11 eyes, the mean ± standard deviation central corneal ECD was 1257 ± 467 cells/mm2 (range, 601-2067 cells/mm2), BCVA improved significantly in 10 treated eyes, the mean visual acuity changed from 0.876 logarithm of the minimum angle of resolution before surgery to 0.046 logarithm of the minimum angle of resolution after surgery, and no major adverse reactions directly related to the hCEC injection therapy were observed. CONCLUSIONS: The findings in this study confirmed the safety and efficacy of cultured hCEC injection therapy for up to 5 years after surgery.

Multi modal imaging in corneal edema after corneal collagen cross-linking (CXL); a case-based literature review.

BACKGROUND: Keratoconus (KCN) is a common ectatic disorder of the cornea. Corneal collagen cross-linking (CXL) is used as an effective option to slowdown the disease progression. Although CXL is considered a safe procedure, corneal endothelial damage, especially in corneal thickness of less than 400 µm, has been reported. CASE PRESENTATION: A 25-year-old man known case of KCN was referred with complaints about blurred vision and discomfort of the right eye 3 days after performing CXL. The preoperative thinnest point was 461 µm. His presenting BCVA was CF at 1 m. Examination showed central corneal edema and stromal haziness. ASOCT demonstrated increased central corneal thickness and very deep CXL line. In the confocal scan, anterior stroma showed hyper-reflective lines without recognizable cells and nerves, the middle stroma showed rare active and edematous keratocytes and a hyper-reflective reticular pattern with elongated keratocytes and needle-like structures involving the posterior stroma indicated increased depth of CXL. To manage the patient, debridement of loosened epithelium was done. Non-preservative steroid 1% eye drop was prescribed frequently. The corneal edema was completely resolved during 2 months with no need for surgical procedure and BCVA of 20/30 in his right eye. CONCLUSION: The corneal thickness of more than 400 µm cannot guarantee the absence of corneal edema after corneal collagen cross-linking, which can pertain to several factors such as inadvertently using of higher energy as well as the incorrect observance of all guidelines, instructions, and other precautions, even by a trained surgeon.

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.

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.

Evaluating the safety and efficacy of compression sutures with intracameral perfluoropropane (C3F8) in the management of acute corneal hydrops.

BACKGROUND: To evaluate the safety and efficacy of using corneal compression sutures with intracameral perfluoropropane (C3F8) in patients presenting with acute corneal hydrops in ectatic disorders. METHODS: A retrospective analysis was done for 43 eyes of patients of acute corneal hydrops, managed using a combination of intracameral 14% C3F8 and full-thickness compression sutures. Time for resolution of edema, corneal thickness (CT) change on anterior segment ocular coherence tomography (ASOCT), and visual outcomes were assessed. RESULTS: Corneal edema resolved with a mean duration of 14.8 ± 3.5 days (range 10-21). The mean CT on ASOCT decreased from a mean of 1437 µm (689-2770 µm) preoperatively to 543 µm (434 -66 µm) on the complete resolution of corneal edema. CONCLUSION: Our results suggest that full-thickness compression sutures and intracameral C3F8 injection can restore the imperviousness of posterior stroma. This technique appears to be a safe and effective technique for faster resolution of corneal edema post hydrops.

[Development in the diagnosis and treatment of Descemet's membrane detachment].

Descemet's membrane detachment (DMD) is a complication of intraocular surgery and is more likely to be seen after cataract surgery. As an intraoperative event, DMD usually features wrinkles and edema on the posterior corneal surface or floating membranoid substance seen in the anterior chamber. Such edema is often seen as surgery-caused corneal edema and membranoid substance as the anterior capsule of the lens. Thus, DMD is easily clinically ignored, even though it is conveniently treated if timely observed. Serious consequences are not uncommon with any delayed diagnosis or treatment. Risk factors include advanced age, previous corneal endothelial lesions and glaucoma, as well as preoperative shallow anterior chamber. Clinical diagnosis is based upon intraoperative judgment, corneal edema diagnosed under a microscope or slit lamp and consequent floating Descemet's membrane. In serious cases, anterior segment OCT and UBM are required. Intracameral injections of air are traditionally adopted in the treatment. In less serious cases, patients see self-healing. (Chin J Ophthalmol, 2021, 57: 143-149).

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.

Reproducibility and reliability of central corneal thickness determination in more and less profound corneal edema using ultrasound pachymetry, a Scheimpflug camera and anterior segment OCT.

PURPOSE: The purpose of this study is to determine the influence of different degrees of corneal edema on the reliability and reproducibility of central corneal thickness(CCT) measurements by a Scheimpflug camera (Pentacam), anterior segment optical coherence tomography(AS-OCT) and ultrasound pachymetry(USP). METHODS: Forty-four patients undergoing ophthalmic surgery were included in this prospective study. All measurements were acquired by two investigators. The Pentacam and AS-OCT measurements were performed in randomized order followed by USP. Two measurements were taken by each investigator with each device. CCT was evaluated by using the apex value provided by the Pentacam, the corneal apex cut in the AS-OCT and averaging 2 cycles of 4 measurements for USP. Coefficients of variation (COV) and intraclass correlation coefficients (ICC) were determined. To investigate the reproducibility in different degrees of corneal edema, patients were subdivided into edema more/less than 10% of CCT, ≥/< 600 µm and > 650 µm CCT. RESULTS: No significant differences were recorded for each individual investigator and measuring device. However, overall the devices differed significantly in the < 600 µm group (ANOVA p < 0.04). The reproducibility decreased with higher degrees of corneal edema in particular for investigator 1 and USP measurements. No significant overestimation of corneal thickness by the Pentacam was recorded in higher degrees of corneal edema. CONCLUSION: USP measurements are highly user dependent especially in higher degrees of corneal edema. Nevertheless, all methods were able to reach a high level of agreement in CCT measurement in higher degrees of corneal edema. Interestingly lower degrees of corneal edema revealed the only significant differences in-between the 3 devices.