Optical coherence tomographic features of feline acute corneal hydrops: A case report.

OBJECTIVE: The objective of the study was to describe the optical coherence tomographic features of a cat with acute corneal hydrops. ANIMAL STUDIED: A 4-year-old castrated male domestic shorthaired showing conjunctival redness, ocular discharge, and intermittent squinting of both eyes with asymmetrical disease onset. METHODS: Complete ophthalmic examination and optical coherence tomography were performed. RESULTS: On slit-lamp biomicroscopic examination, severe intrastromal fluid pockets with profound bullae were observed in the dorsomedial region in both eyes. A diagnosis of feline acute corneal hydrops was made in both eyes. Optical coherence tomography revealed profound stromal lamellar separation representing heterogeneous reflective areas, and fluid pockets and bullae of variable size were concomitant to Descemet's membrane detachment demonstrated by a well-defined homogeneous hyporeflective area. Upon reevaluation 30 days during healing process for both eyes, the thickened epithelia and the thinning pan-stromal areas were identified as homogeneously hyper-reflective epithelia and as heterogeneous hyper-reflectivity, respectively. A thickened posterior corneal surface was shown as heterogeneous with patchy hyper-reflectivity. Additionally, Descemet's membrane detachment in the initial presentation had two distinct forms suspicious of Descemet's membrane rupture in each eye: a break with rolled ends and a break with flat ends. CONCLUSION: To the author's knowledge, this study represents the first documentation of in vivo detection of Descemet's membrane detachment and presumed rupture in a cat experiencing acute corneal hydrops. These observations strongly indicate that Descemet's membrane detachment/rupture acts as a most likely risk factor in the onset of acute corneal hydrops in cats.

Descemet's membrane folds in ochronosis: a case report.

BACKGROUND: We present this report of a new ophthalmic finding in a patient with ochronosis. CASE PRESENTATION: An 85-year-old Caucasian male patient with bilateral dark temporal and nasal pigmentation of conjunctiva and sclera was referred to our hospital owing to low visual acuity. On biomicroscopic examination, bilateral horizontal Descemet's membrane folds were observed. Corneal tomography revealed irregular and asymmetric "against-the-rule" astigmatism in both eyes. Anterior segment optical coherence tomography demonstrated numerous central Descemet's without edema or other corneal structure alterations. CONCLUSION: This is the first report of Descemet's membrane folds in ochronosis. These corneal findings suggest that the accumulation of homogentisic acid in the sclera leads to thickening and stiffness of this region. These alterations could remarkably decrease visual acuity owing to topographic corneal curvature alterations, especially in elderly patients.

Effect of Descemet Membrane Endothelial Keratoplasty Graft Storage Time on Graft Elasticity.

PURPOSE: The purpose of this study was to evaluate the effect of Descemet membrane endothelial keratoplasty (DMEK) graft storage time on its elastic properties, measured using atomic force microscopy (AFM). METHODS: Twenty human corneas (from 10 donors), unsuitable for transplantation, were obtained from the eye bank (S. Fyodorov Eye Microsurgery State Institution, Moscow). Ten DMEK grafts were prepared and stored in the corneal storage medium, Optisol-GS at 4°C after preparation, and AFM analysis was performed within 12 hours after preparation (group A). Ten paired corneas from the respective donors were stored in Optisol-GS at 4°C for 1 week after preparation before AFM analysis (group B). Data were analyzed using the Hertz model for the evaluation of the Young modulus of elasticity. RESULTS: Force-distance curve analysis showed an increase in the Young modulus of elasticity in group B in comparison with that in group A, and the mean values were 10.4 ± 1.8 kPa and 6.77 ± 2.25 kPa, respectively (P < 0.001). There was no correlation between the Young modulus of elasticity and donor age (r = 0.110, P = 0.644), endothelial cell count (r = -0.145, P = 0.541), and procurement interval (r = 0.14, P = 0.755). CONCLUSIONS: A longer graft storage time in cold storage medium was found to significantly reduce the elasticity of the DMEK graft. Clinically, this could potentially influence the unfolding of the DMEK graft within the anterior chamber during surgery and the postoperative detachment rate.

[Imaging features of posterior polymorphous corneal dystrophy observed by in vivo confocal microscopy].

Objective: To identify and analyze imaging features of posterior polymorphous corneal dystrophy (PPCD) by in vivo confocal microscopy (IVCM). Methods: This retrospective case series enrolled 27 eyes of 18 patients (including 10 males and 8 females) who were diagnosed with PPCD at the Department of Ophthalmology in Peking University Third Hospital between January 2013 and December 2019. The mean age was (23.61±14.81) years. There were 9 monocular and 9 binocular cases. All patients were examined by slit-lamp biomicroscopy and IVCM. The visual acuity, the mean endothelial cell density, and the images of IVCM were analyzed in all cases. Results: The mean best-corrected visual acuity was 0.76±0.33, and the mean endothelial cell density was (1 723.6±698.3) cells/mm2. The IVCM images of type 1 PPCD (vesicular lesions) showed hyperreflective, placoid or homocentric lesions at the level of the Descemet's membrane, hyporeflective, oval or round lesions at the level of the Descemet's membrane, and hyporeflective, crater-like lesions at the level of the endothelial cell layer. The IVCM images of type 2 PPCD (band lesions) displayed hyperreflective, band lesions and a fibrous strand structure at the level of the Descemet's membrane, hyporeflective, vesicular lesions at the level of the Descemet's membrane, and hyporeflective, trough-and ridge-like lesions at the level of the endothelial cell layer. The IVCM images of type 3 PPCD (geographic placoid opacities) showed loss of the hexagonal features of endothelial cells and epithelial-like cell transformation. Conclusions: PPCD primarily affects the endothelium and Descemet's membrane. IVCM could highlight the special characteristics of PPCD including hyperreflective lesions at the level of the Descemet's membrane, hyporeflective lesions at the level of the endothelial cell layer, and epithelial-like cell transformation of endothelial cells. IVCM is an invaluable tool for clinical diagnosis and dynamic monitoring of PPCD.

Region of Interest Densitometry Analysis of Descemet Membrane Endothelial Keratoplasty Dehiscence on Anterior Segment Optical Coherence Tomography.

Purpose: To evaluate a region of interest (ROI) method of analyzing anterior segment optical coherence tomography (AS-OCT) corneal densitometry (CD) in the setting of Descemet membrane endothelial keratoplasty (DMEK) dehiscence. Methods: Retrospective chart review of eyes that underwent (1) DMEK for Fuchs dystrophy (2) between 2018 to 2020 with (3) a partial DMEK dehiscence on AS-OCT, (4) involvement of only one side of the graft, (5) high-quality corneal AS-OCT scan, and (6) location of dehiscence within the central 5.5 mm of the cornea. Image analysis of the ROIs with ImageJ compared the total edematous area, mean stromal CD, and ratio of anterior-to-posterior (A/P) stromal CD for regions of DMEK dehiscence compared to the contralateral side with an attached DMEK graft. Control regions (with no dehiscence) and postdehiscence resolution images were also analyzed. Results: Seventy sectors of the 21 images from 21 eyes with DMEK dehiscence were included. Compared to the contralateral side, regions of DMEK dehiscence had larger total areas (P < 0.0001), lower mean stromal CD (P = 0.0003), and higher A/P stromal CD (P < 0.0001). All control regions and postdehiscence resolution images did not show any significant differences compared to the contralateral sides. Conclusions: This technique to analyze multiple ROIs on AS-OCT can be useful to evaluate CD of specific regions of corneal pathology. Lower mean stromal CD and higher A/P stromal CD may specify corneal edema. Translational Relevance: Analyzing CD via multiple specific ROIs may be more suitable than measuring the CD of the full cornea and has broader applications extending to other corneal pathologies.

Spontaneous attachment of complex Descemet's membrane detachment following multiple failed interventions.

We describe a case with complex Descemet membrane detachment (DMD) which persisted despite initial two failed surgical attempts to appose the ocular tissues. However, over time, tissue alignment was obtained spontaneously. A 60-year-old woman, operated trabeculectomy, had a total DMD intraoperatively during a complicated cataract surgery. Initial attempt to DM repositioning with intracameral air injection failed. Anterior Segment Optical Coherence Tomography (ASOCT) showed detachment of both DM and pre-Descemet's layer (PDL). After consultation with a corneal surgeon, patient was again attempted for Intra-operative Optical Coherence Tomography (iOCT)-guided settlement of DMD with intracameral air which again failed. So, the patient was registered for lamellar corneal transplant, but at 3 months follow-up, DM had spontaneously attached, confirmed on ASOCT. This case shows for the first time that even complex DMDs involving PDL, can spontaneously appose despite failed surgical interventions.

Prediction of corneal graft rejection using central endothelium/Descemet's membrane complex thickness in high-risk corneal transplants.

To determine whether measurements of Endothelium/Descemet complex thickness (En/DMT) are of predictive value for corneal graft rejection after high-risk corneal transplantation, we conducted this prospective, single-center, observational case series including sixty eyes (60 patients) at high risk for corneal graft rejection (GR) because of previous immunologic graft failure or having at least two quadrants of stromal vascularization. Patients underwent corneal transplant. At 1st, 3rd, 6th, 9th, and 12th postoperative month, HD-OCT imaging of the cornea was performed, and the corneal status was determined clinically at each visit by a masked cornea specialist. Custom-built segmentation tomography algorithm was used to measure the central En/DMT. Relationships between baseline factors and En/DMT were explored. Time dependent covariate Cox survival regression was used to assess the effect of post-operative En/DMT changes during follow up. A longitudinal repeated measures model was used to assess the relationship between En/DMT and graft status. Outcome measures included graft rejection, central Endothelium/Descemet's complex thickness, and central corneal thickness (CCT). In patients with GR (35%), the central En/DMT increased significantly 5.3 months (95% CI: 2, 11) prior to the clinical diagnosis of GR, while it remained stable in patients without GR. During the 1-year follow up, the rejected grafts have higher mean pre-rejection En/DMTs (p = 0.01), compared to CCTs (p = 0.7). For En/DMT ≥ 18 µm cut-off (at any pre-rejection visit), the Cox proportional hazard ratio was 6.89 (95% CI: 2.03, 23.4; p = 0.002), and it increased to 9.91 (95% CI: 3.32, 29.6; p < 0.001) with a ≥ 19 µm cut-off. In high-risk corneal transplants, the increase in En/DMT allowed predicting rejection prior to the clinical diagnosis.

Corneal pachymetry by AS-OCT after Descemet's membrane endothelial keratoplasty.

Corneal thickness (pachymetry) maps can be used to monitor restoration of corneal endothelial function, for example after Descemet's membrane endothelial keratoplasty (DMEK). Automated delineation of the corneal interfaces in anterior segment optical coherence tomography (AS-OCT) can be challenging for corneas that are irregularly shaped due to pathology, or as a consequence of surgery, leading to incorrect thickness measurements. In this research, deep learning is used to automatically delineate the corneal interfaces and measure corneal thickness with high accuracy in post-DMEK AS-OCT B-scans. Three different deep learning strategies were developed based on 960 B-scans from 50 patients. On an independent test set of 320 B-scans, corneal thickness could be measured with an error of 13.98 to 15.50 µm for the central 9 mm range, which is less than 3% of the average corneal thickness. The accurate thickness measurements were used to construct detailed pachymetry maps. Moreover, follow-up scans could be registered based on anatomical landmarks to obtain differential pachymetry maps. These maps may enable a more comprehensive understanding of the restoration of the endothelial function after DMEK, where thickness often varies throughout different regions of the cornea, and subsequently contribute to a standardized postoperative regime.

Single-Pass Mikrokeratome and Anterior Chamber Pressurizer for the Ultrathin Descemet-Stripping Automated Endothelial Keratoplasty Graft Preparation.

PURPOSE: To compare the reliability of microkeratome dissection with the anterior chamber pressurizer (ACP) system versus conventional pressurization for ultrathin Descemet-stripping automated endothelial keratoplasty (UT-DSAEK) graft preparation. METHODS: A retrospective review of a consecutive series of dissected donor corneas processed at Pavia Eye Bank for UT-DSAEK surgery was performed. Grafts were prepared through single-pass microkeratome dissection with artificial anterior chamber internal pressure regulation through either ACP or the conventional method using a water column with tube clamp. The target central graft thickness (CGT) was ≤100 µm. Cutting predictability was determined as the difference between the microkeratome head size and the thickness actually removed. Graft regularity was investigated as central-to-peripheral thickness increase, central-to-peripheral (CP) ratio, and graft thickness uniformity. Thickness was measured with anterior segment optical coherence tomography (horizontal and vertical meridians). RESULTS: Of the 265 UT-DSAEK grafts, ACP achieved the target "CGT ≤ 100 µm" in 87 of 120 (72.5%), whereas the conventional technique achieved the same in 85 of 145 (58.6%) (P = 0.018). ACP predictability was -3.9 µm (SD: 2.3), whereas predictability of the conventional technique was -54.6 µm (SD: 3.7) (P < 0.001). Thickness increased similarly (P = 0.212); CP ratio was better with ACP for only 2 mm diameter (P = 0.001); graft thickness uniformity was comparable (P > 0.05). CONCLUSIONS: Compared with conventional pressurization, ACP improved microkeratome-assisted preparation reliability of UT-DSAEK grafts, achieving CGT ≤ 100 µm with significantly higher frequency (P = 0.018) and predictability (P < 0.001). ACP improved CP ratio only at 2 mm (P = 0.001); for other graft thickness, the 2 methods proved equivalent.

[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).

The Descemet Membrane in Primary Congenital Glaucoma.

PURPOSE: To evaluate Descemet membrane (DM) morphology in eyes with primary congenital glaucoma (PCG) in vivo using high-definition anterior segment optical coherence tomography (ASOCT) and on histopathology. METHODS: Corneal scans of patients with PCG (22 eyes of 15 patients) were evaluated for DM morphology and anterior chamber angle using ASOCT. The DM thickness in PCG eyes was compared with fellow eyes (8 eyes) of unilateral patients with PCG and healthy controls (12 eyes) on ASOCT. The DM morphology was also compared on the histopathology of corneal tissues (9) obtained from PCG eyes after keratoplasty and enucleated eyes of retinoblastoma (6 controls) on light microscopy with immunostaining for collagen IV. RESULTS: On ASOCT, all affected eyes showed the presence of either a thickened DM complex or a hyper-reflective double layer representing the thickened DM and pre-Descemet layer (PDL), unlike a single membrane in the controls and fellow eyes. On ASOCT, among patients with PCG, the DM showed significant thickening (32.0 ± 11.2 µm) versus fellow eyes (14.4 ± 3.3 µm) and controls (11.5 ± 1 µm) (P < 0.001; analysis of variance). The thickened DM complex continued peripherally into the trabecular meshwork as an abnormal membrane in 16/22 affected eyes. On histopathology, thickening of DM was also more among PCG eyes (median: 67.9 µm range: 27.2-214.9) versus controls (median: 27.7 µm, range: 22.1-36.1; P = 0.005) as also of PDL (median: 14 µm, range: 5.9-30.5) of PCG versus (median 3.5, range: 1.3-6.7 µm) in controls; P = 0.014. CONCLUSIONS: Thickening of DM and PDL occurs in eyes with PCG and is seen to have a peripheral extension upto the angle recess.

Standardized pachymetry-assisted manual lamellar dissection for Descemet stripping endothelial keratoplasty.

PURPOSE: To present an alternative technique (Pachy-DSEK) for the manual preparation of thin endothelial lamellae in Descemet stripping endothelial keratoplasty (DSEK), as well as to evaluate its visual and anatomic outcomes. METHODS: A retrospective chart review was conducted in 15 cases who underwent DSEK at a private eye clinic in Brazil (INOB, Brasília) from June 2017 to December 2019. All patients had ocular comorbidities and relative contraindications to Descemet membrane endothelial keratoplasty (DMEK). All endothelial lamellae were manually prepared by using a standardized technique. Best corrected visual acuity (BCVA), tomographic parameters and graft's thickness were evaluated preoperatively and at 6 months. Endothelial cell counts were evaluated preoperatively and at 12 to 24 months. RESULTS: During preparation there was one case (6%) of peripheral tear and no tissue was lost. At 6 months, the median BCVA improved from 1.60 to 0.40 logMAR (p = 0.0009). There was no significant change in anterior (p = 0.507) and posterior astigmatism (p = 0.483), anterior (p = 0.683) and posterior mean keratometry (p = 0.767), and total corneal power (p = 0.952). The median central graft thickness at 6 months was 80 µm. Ultrathin grafts (<130 µm) were achieved in 80% of cases. At 12 to 24 months endothelial cell count decreased significantly. Graft's detachment occurred in two cases (13%) and endothelial rejection in one case (6%). CONCLUSION: By using ultrasonic pachymetry intra-operatively and standardizing graft preparation, most manually dissected endothelial lamellae were ultrathin. Pachy-DSEK was safe and effective for treating endothelial disfunction in eyes with ocular comorbidities. It may be a cost-effective alternative to automated dissection methods.

Central retinal artery occlusion after Descemet membrane reposition by intracameral air: A case report.

PURPOSE: To report a case of central retinal artery occlusion after Descemet membrane reposition by intracameral air. METHODS: An otherwise healthy 60-year-old woman presented with white mature cataract in her left eye. Ocular exam of both eyes was within normal limits. After an uneventful topical phacoemulsification, a moderate-grade striate keratopathy and non-planar Descemet membrane detachment was noted on first postoperative day, which was confirmed on anterior segment optical coherence tomography. The Descemet membrane was repositioned within 24 h of cataract extraction by intracameral air tamponade (pneumatic descematopexy) under topical anesthesia, and partial air release was done after 2 h. The patient was evaluated for decreased immediate postoperative vision of perception of light. RESULTS: After pneumatic descematopexy, the stromal edema relatively cleared. The intraocular pressure before releasing the intracameral air was 38 mmHg and antiglaucoma medication was started. Dilated fundus exam showed retinal pallor and a cherry-red spot over the macula. A diagnosis of central retinal artery occlusion was confirmed, and thorough systemic workup was done. Systemic investigations were within normal limits. The patient was managed conservatively, but the final visual acuity remained at 1/60. CONCLUSION: Central retinal artery occlusion is not a reported complication after pneumatic descematopexy for Descemet membrane detachment management. The possible mechanism could be sudden increase in intraocular pressure due to pupil block by air, and thus, ocular surgeries with use of intracameral air for prolonged duration warrants close monitoring of intraocular pressure and its subsequent management.