Deep Learning Model for the Detection of Corneal Edema Before Descemet Membrane Endothelial Keratoplasty on Optical Coherence Tomography Images.

Purpose: Descemet membrane endothelial keratoplasty (DMEK) is the preferred method for treating corneal endothelial dysfunction, such as Fuchs endothelial corneal dystrophy (FECD). The surgical indication is based on the patients' symptoms and the presence of corneal edema. We developed an automated tool based on deep learning to detect edema in corneal optical coherence tomography images. This study aimed to evaluate this approach in edema detection before Descemet membrane endothelial keratoplasty surgery, for patients with or without FECD. Methods: We used our previously described model allowing to classify each pixel in the corneal optical coherence tomography images as "normal" or "edema." We included 1992 images of normal and preoperative edematous corneas. We calculated the edema fraction (EF), defined as the ratio between the number of pixels labeled as "edema," and those representing the cornea for each patient. Differential central corneal thickness (DCCT), defined as the difference in central corneal thickness before and 6 months after surgery, was used to quantify preoperative edema. AUC of EF for the edema detection was calculated for Several DCCT thresholds and a value of 20 µm was selected to define significant edema as it provided the highest area under the curve value. Results: The area under the curve of the receiver operating characteristic curve for EF for the detection of 20 µm of DCCT was 0.97 for all patients, 0.96 for Fuchs and normal only and 0.99 for non-FECD and normal patients. The optimal EF threshold was 0.143 for all patients and patients with FECD. Conclusions: Our model is capable of objectively detecting minimal corneal edema before Descemet membrane endothelial keratoplasty surgery. Translational Relevance: Deep learning can help to interpret optical coherence tomography scans and aid the surgeon in decision-making.

Regular and irregular astigmatism of bullous keratopathy using Fourier harmonic analysis with anterior segment optical coherence tomography.

Bullous keratopathy (BK) is known to present with corneal edema and Descemet's folds, which can cause corneal astigmatism. However, no report quantitatively evaluated BK astigmatism by separating it into regular and irregular astigmatism. This study investigated the regular and irregular astigmatism of the anterior and posterior corneal surface with Fourier harmonic analysis and anterior segment optical coherence tomography. Preoperative data from 43 eyes of 41 BK patients who received corneal endothelial transplantation were compared with the data from 43 eyes of 43 subjects without corneal disease. Anterior and posterior cylinder power, central corneal thickness (CCT) and thinnest corneal thickness were significantly greater in BK. With Fourier harmonic analysis, BK eyes were found to have significantly larger anterior and posterior regular astigmatism, asymmetry component and higher-order irregularity. Asymmetry component and higher-order irregularity that accounted for the posterior irregular astigmatism increased as CCT increased in BK. Higher-order irregularity in the posterior cornea also positively correlated with worsening best corrected visual acuity. Subgroup analysis found significant correlations between CCT and posterior higher-order irregularity for intraocular surgery and laser iridotomy, but not Fuchs endothelial corneal dystrophy. This study has significance in that it revealed the characteristics of the corneal posterior irregular astigmatism of BK.

A Case Of Descemet Membrane Detachment Postcataract Surgery.

Descemet Membrane Detachment is a vision-threatening complication of Cataract Surgery. If not treated promptly it can lead to serious vision impairment with the possible need for corneal transplantation. We present a case report of a 60 years old female who presented with blurry vision post phacoemulsification and lens placement after a cataract in the left eye. She was diagnosed with Descemet membrane detachment on slit-lamp examination that was confirmed on Anterior-segment Optical Coherence Tomography and treated with intracameral 20% SF6 injection. There was a marked improvement in her vision with complete resolution of corneal oedema. Conclusion: Anterior Segment OCT can be used as a diagnostic tool to accurately ascertain the site and extent of detachment and monitor disease progress. 20% Sulfur-hexafluoride intracameral injection can be used as a surgical option for large, central detachments.

Mini-Descemet Membrane Endothelial Keratoplasty for the Early Treatment of Acute Corneal Hydrops in Keratoconus.

PURPOSE: To describe a new surgical option for the treatment of acute corneal hydrops in keratoconus and to present the first results. METHODS: This is a retrospective analysis of 3 patients who presented to our clinic with a massive corneal hydrops in acute keratoconus and were treated by mini-Descemet membrane endothelial keratoplasty (DMEK). According to the size and the shape of the gap in the patient's Descemet membrane (DM), 1 DMEK graft was trephined with a round 5-mm punch. The other grafts were trimmed with a razor blade to a width of about 3 mm and a length adjusted to the length of the defect of the recipients' DM. The graft was inserted with a regular intraocular lens shooter. Correct unfolding of the graft was controlled by using intraoperative optical coherence tomography. At the end of the surgery, the graft was attached to the posterior corneal surface by a small air bubble. Thereafter, the complete anterior chamber was filled with 20% SF6 gas. RESULTS: All 3 patients (age 32 ± 3 years on average) showed a rapid increase in uncorrected visual acuity from the logarithm of the minimum angle of resolution (LogMAR) 1.66 (±0.46) before mini-DMEK to the LogMAR 1.2 (±0.3) within 6 to 8 weeks after mini-DMEK. The thickest corneal point within the edematous cornea decreased in all 3 patients (1088 ± 280 µm before surgery vs. 630 ± 38 µm 1 week after surgery). One mini-DMEK failed in a first attempt. In this patient, the recipient DM was under strong tension and showed a pronounced dehiscence. Therefore, a small part of the recipient's DM around the preexisting gap in DM was removed before a second mini-DMEK graft was placed successfully. The other 2 patients developed partial graft detachment within 1 to 2 weeks after surgery. However, the corneas of these patients were dehydrated to physiological levels after mini-DMEK, and despite partial detachment, there was no relapse of the hydrops. CONCLUSIONS: Mini-DMEK could be helpful in patients with larger defects and detachments of DM in very ectatic corneas in the acute phase of corneal hydrops in acute keratoconus. These patients may not be successfully treated by intracameral gas application alone or in combination with pre-Descemetal sutures. Further investigations are needed to identify factors helping to decide on the best surgical approach in hydrops in acute keratoconus.

Microscope-Integrated Optical Coherence Tomography-Guided Drainage of Acute Corneal Hydrops in Keratoconus Combined With Suturing and Gas-Aided Reattachment of Descemet Membrane.

PURPOSE: The treatment of acute corneal hydrops due to keratoconus has so far been limited to awaiting the spontaneous resorption of corneal edema, supportive care, and finally keratoplasty. A recent publication describes the surgical reattachment of Descemet Membrane (DM) facilitated by pre-Descemetic sutures and anterior chamber air/gas filling. Here, we present a novel microscope-integrated intraoperative optical coherence tomography (MI-OCT)-guided technique for the immediate reattachment of DM in corneal hydrops due to keratoconus in 2 male patients with small central DM defects. METHODS: Case series of 2 consecutive patients with acute corneal hydrops due to keratoconus. The novel technique consists of the MI-OCT-guided puncture and drainage of intrastromal fluid pockets combined with anterior chamber sulfur hexafluoride-fill and pre-descemetic sutures using a commercially available MI-OCT (iOCT; Haag Streit Surgical, Wedel, Germany). RESULTS: After uneventful surgery, corneal edema showed fast resolution and DM was reattached to the corneal stroma. In both patient's central corneal thickness decreased after surgery and visual acuity improved. CONCLUSIONS: MI-OCT guided micropuncture of stromal edema combined with compression sutures and SF6 tamponade is a new therapeutic option in acute corneal hydrops with small Descemet membrane defects.

Treatment of Severe Keratoconus Hydrops With Intracameral Platelet-Rich Plasma Injection.

PURPOSE: To present successful management of severe corneal hydrops by corneal optical coherence tomography (OCT) guidance and intracameral application of eye platelet-rich plasma (E-PRP) in a case with Down syndrome. METHODS: A 36-year-old woman with Down syndrome presented with acute vision loss, pain, photophobia, and corneal edema in the left eye. Clinical examination revealed keratoconus in the right eye and extreme keratoconus with severe corneal hydrops in the left eye. Anterior segment OCT (MS-39, Costruzione Strumenti Oftalmici, Firenze, Italy) showed intrastromal cystic fluid collection and ruptured and detached Descemet membrane. The OCT-guided management of hydrops is first described in this case report. RESULTS: Medical treatment and intracameral sulfur hexafluoride injection failed. A sterile 0.3 mL of E-PRP was injected into the anterior chamber. Clinical and anatomical improvement began from the first postoperative day, and corneal edema totally resolved at 1 week. Postoperatively, no significant side effect was noted except an early transient moderate (28 mm Hg) intraocular pressure peak. Anterior segment-OCT demonstrated dramatic normalization in corneal morphology with total disappearance of fluid in the cystic intracorneal space, closure of the DM rupture, and DM reattachment. The patient was stable during the 6-month follow-up. CONCLUSIONS: In this case, intraocular E-PRP was a promising, apparently safe, and effective treatment option in management of corneal hydrops, in which conventional approaches failed. This is the first case in the literature to describe OCT appearance of corneal hydrops and intracameral use of E-PRP for the resolution of DM rupture in acute corneal hydrops.

Quantitative evaluation of corneal epithelial edema after cataract surgery using corneal densitometry: a prospective study.

PURPOSE: The optical density of the cornea can be evaluated quantitatively by "densitometry" using a rotating Scheimpflug camera. Densitometry allows evaluation of corneal opacity in the anterior segment of the eye by quantitative measurement of scattering light. In the present investigation, we evaluate quantitatively minimal subclinical corneal edema after cataract surgery using densitometry. METHODS: Fifty four eyes of 34 patients who underwent cataract surgery were enrolled. Measurement of corneal density was performed using Pentacam® before and on days 1, 3 and 7 after surgery. RESULTS: Densitometry scores increased from 18.12 ± 1.76 before cataract surgery to 21.03 ± 3.84 on day 1 (P < 0.001) and 19.90 ± 2.46 on day 3 (P = 0.018), but recovered to 19.44 ± 1.58 on day 7 (P = 0.131). Total corneal thickness was 549.1 ± 32.7 µm before surgery and increased to 582.7 ± 46.3 µm on day 1 (P = 0.001), but recovered to 566.4 ± 29.7 µm on day 3 (P = 0.097). Densitometry reading correlated positively with corneal thickness (correlation coefficient = 0.13, P = 0.003). CONCLUSIONS: Densitometry is useful to detect corneal edema that is not detectable by slit-lamp examination.

Case Report: Acute Hydrops with Descemet Membrane Schisis in Corneal Ectasia after Radial Keratotomy.

SIGNIFICANCE: As patients with previous radial keratotomy (RK) are still occasionally encountered, recognition of the anatomy of post-RK corneas and management of their complications remain relevant. High-definition anterior segment optical coherence tomography (AS-OCT) is a very useful tool to assess these postsurgical corneas. PURPOSE: To describe a case of acute corneal hydrops with Descemet membrane schisis after RK with observation by AS-OCT. CASE REPORT: A 43-year-old woman presented with a 9-day history of sudden vision loss, foreign body sensation, and photophobia in her left eye. She had undergone bilateral RK 25 years ago at her local hospital. Slit-lamp examination revealed marked corneal edema and stromal clefts in the central cornea along with radial surgical scars in her left eye. Pentacam imaging showed the typical pattern of a post-RK cornea with ectasia in her right eye. Multiple dilacerations of collagen lamellae and fluid-filled intrastromal cysts together with epithelial edema were observed in her left eye using AS-OCT. A Descemet membrane detachment with schisis was also shown by AS-OCT. After 5 months of medication with topical 0.1% fluorometholone eye drops four times daily together with 3% ofloxacin eye ointment once daily, the corneal edema, Descemet membrane detachment, and Descemet membrane schisis had completely resolved resulting in pan-stromal scarring. CONCLUSIONS: This report describes acute corneal hydrops with Descemet membrane schisis after RK imaged using high-definition AS-OCT. The acute hydrops was possibly caused by corneal ectasia or underlying keratoconus, which was aggravated by RK. High-definition AS-OCT is a useful tool to demonstrate the details of different corneal layers and to observe the resolving process of acute hydrops. Topical medications consisting of antibiotic, lubrication, and corticosteroid can be used to treat the acute event effectively.

Impact of Ophthalmic Surgeon Experience on Early Postoperative Central Corneal Thickness After Cataract Surgery.

PURPOSE: To assess the impact of surgeon experience on early postoperative central corneal thickness (CCT) in eyes that have undergone phacoemulsification-based cataract surgery. METHODS: One hundred sixty eyes underwent phacoemulsification-based cataract surgery performed by an experienced surgeon (n = 110; senior group) or a surgically less experienced ophthalmic assistant (n = 50; junior group), using the divide-and-conquer or tilt-and-tumble technique for cataractous lens extraction. The primary endpoint was postoperative corneal edema 2 hours after surgery, determined by pachymetry-based CCT. RESULTS: Mean age of patients was 71.5 ± 9.1 years. Mean CCT at postoperative hour 2 was 622.8 ± 69.3 µm: an increase of 14.3% ± 10.8 from 545.3 ± 33.7 µm preoperatively (P = 0.0028). Mean CCT at postoperative hour 2 and postoperative corneal edema were significantly higher for the junior group than the senior group, with mean respective increases of 105.8 ± 81.4 µm (19.3% ± 14.2%) and 66.4 ± 3.7 µm (12.3% ± 8.3%), P = 0.0001. After adjustment for confounding factors, surgical experience was the only factor significantly associated with corneal edema: ß = 39.58; SD = 11.05; P = 0.0005. Other intergroup differences observed included significantly longer mean operating and mean ultrasound times in the junior group than in the senior group. A final corneal suture was used more frequently in the senior than in the junior group, at rates of 32.7% and 2.0%, respectively, P < 0.0001. CONCLUSIONS: Greater surgical experience was found to be associated with reduced early postoperative corneal edema, shorter operative time, and shorter ultrasound time. This suggests that beyond mastering the initial learning curve of phacoemulsification, surgical experience enables faster and safer surgery.

Superficial Keratectomy and Conjunctival Advancement Hood Flap (SKCAHF) for the Management of Bullous Keratopathy: Validation in Dogs With Spontaneous Disease.

PURPOSE: To evaluate the efficacy of superficial keratectomy and conjunctival advancement hood flap (SKCAHF) for the treatment of bullous keratopathy in canine patients. METHODS: Nine dogs (12 eyes) diagnosed with progressive corneal edema underwent superficial keratectomy followed by placement of conjunctival advancement hood flaps. The canine patients were examined pre- and postoperatively using in vivo confocal microscopy, ultrasonic pachymetry (USP), and Fourier-domain optical coherence tomography (FD-OCT). All owners responded to a survey regarding treatment outcomes. RESULTS: Mean central corneal thickness (CCT) as measured by FD-OCT was 1163 ± 290 µm preoperatively and significantly decreased postoperatively to 795 ± 197 µm (P = 0.001), 869 ± 190 µm (P = 0.005), and 969 ± 162 µm (P = 0.033) at median postoperative evaluations occurring at 2.2, 6.8, and 12.3 months, respectively. Owners reported significant improvement (P < 0.05) in vision and corneal cloudiness at 6.8 and 12.3 months postoperatively. The percentage of cornea covered by the conjunctival flap was correlated (P = 0.0159) with a reduction in CCT by USP at 12.3 months postoperatively. All canine patients were comfortable pre- and postoperatively. CONCLUSIONS: SKCAHF results in a reduction of corneal thickness in canine patients with bullous keratopathy. The increase in corneal thickness over time, after performing SKCAHF, is likely because of progressive endothelial decompensation. This surgery is a potentially effective intervention for progressive corneal edema in dogs that may have value in treatment of human patients with bullous keratopathy.

Near-term analysis of corneal epithelial thickness after cataract surgery and its correlation with epithelial cell changes and visual acuity.

PURPOSE: To quantify corneal central epithelial thickness and cell changes 2 weeks after cataract surgery and correlate it with corrected distance visual acuity (CDVA). SETTING: Eye and ENT Hospital of Fudan University, Shanghai, China. DESIGN: Prospective observational study. METHODS: Patients having cataract surgery were assessed preoperatively and 1, 2, 3, 5, 7, and 14 days postoperatively. Anterior segment spectral-domain optical coherence tomography and corneal confocal laser scanning microscopy were used to measure central epithelial thickness, central corneal thickness (CCT), corneal basal epithelial cell density, and Langerhans cell density. RESULTS: The CCT and central epithelial thickness were significantly increased on 1 day postoperatively. From 1 day to 14 days, the CCT gradually decreased but was greater than the baseline value, whereas the central epithelial thickness declined to near baseline values at 3 days, became thinner at 5 and 7 days, and then returned to baseline at 14 days. The corneal basal epithelial cell density increased significantly postoperatively. Significant Langerhans cell infiltration was seen at 3 days and 5 days. Significant correlations were found between CDVA and the central epithelial thickness and CCT. The maximum increase in central epithelial thickness and CCT correlated with the lowest achieved values of CDVA postoperatively. Patients with significant edema at 1 day had worse CDVA at 14 days. CONCLUSIONS: Near-term epithelial remodeling occurred, initially appearing as a thickening that might be attributed to edema. This was followed by thinning, possibly caused by inflammation, and finally reaching baseline levels. Edema of the corneal epithelium was related to visual recovery after cataract surgery.

Central corneal thickness considered an index of corneal hydration of the UVB irradiated rabbit cornea as influenced by UVB absorber.

UVB radiation from sunlight induces an acute corneal inflammation, photokeratitis, accompanied by changes in corneal hydration. We employed a method of ultrasonic pachymetry for daily examination of central corneal thickness as an index of corneal hydration of the rabbit cornea repeatedly irradiated by UVB radiation (312 nm, daily dose of 0.25 J/cm(2) during three or four days) as influenced by UVB absorber (actinoquinol combined with hyaluronic acid) dropped on the ocular surface during irradiation. One day after the third irradiation procedure the animals were sacrificed and corneas examined immuno-histochemically for peroxynitrite formation, a marker of oxidative damage, the antioxidant aldehyde dehydrogenase 3A1 and endothelial nitric oxide synthase, an enzyme generated nitric oxide. Results show that UV absorber combined with hyaluronic acid protected the cornea against UVB-induced changes in corneal thickness and microscopical disturbances to the cornea (both seen after buffered saline application) until the fourth experimental day. These UVB doses are equivalent to a daily exposure of 2.5 hrs of the human cornea to solar UVB radiation for three consecutive days. It is suggested that actinoquinol/ hyaluronic acid drops might be helpful for the human eye in the defence against photooxidative and other oxidative processes.

Modulation of central corneal thickness by various riboflavin eyedrop compositions in porcine corneas.

PURPOSE: To evaluate the modulatory effect of various riboflavin 0.1% and 0.2% compositions on the central corneal thickness (CCT) in fresh porcine corneas. SETTING: Department of Ophthalmology, Johannes Gutenberg University of Mainz, Mainz, Germany. DESIGN: Experimental study. METHODS: The CCT in freshly enucleated porcine globes was measured by ultrasound pachymetry before and after (if applicable) deepithelialization and every 10 minutes thereafter during 120 minutes of eyedrop application. In Groups 1 and 2 (controls), no eyedrops were applied. In Groups 3 and 4, isotonic riboflavin eyedrops were used. In Groups 5 to 9, hypotonic riboflavin eyedrops were given. In Groups 10 and 11, preparations for transepithelial crosslinking were applied. In Groups 2 to 9, deepithelialization was performed. The final CCT in the groups was compared by analysis of variance. RESULTS: One hundred ten freshly enucleated porcine globes were used. The mean final CCT compared with preoperative values was 97% ± 4% (SD) in Group 1, 91% ± 4% in Group 2, 66% ± 5% in Group 3, 151% ± 13% in Group 4, 65% ± 2% in Group 5, 105% ± 3% in Group 6, 120% ± 4% in Group 7, 130% ± 4% in Group 8, 132% ± 4% in Group 9, 114% ± 2% in Group 10, and 114% ± 4% in Group 11. The differences between Group 1 and each of Groups 3, 4, 5, 7, 8, and 9 were statistically significant (P<.05). CONCLUSION: There was considerable variation in the final CCT as a result of varying riboflavin eyedrop compositions. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Ultrasound biomicroscopy-guided assessment of acute corneal hydrops.

OBJECTIVE: To analyze the morphologic features of acute hydrops and treatment success using ultrasound biomicroscopy (UBM). DESIGN: Prospective interventional case series. PARTICIPANTS: Fourteen patients (14 eyes) affected by keratoconus with acute corneal hydrops. INTERVENTION: Patients with acute hydrops were treated with intracameral injection of 0.15 ml of 14% perfluoropropane (C3F8) gas. MAIN OUTCOME MEASURES: The parameters evaluated on UBM included the location and length of the Descemet's membrane (DM) tear and corneal thickness at the central corneal thickness at the area overlying the DM tear (CT0), corneal thickness 2.5 mm from the central point (CT2.5), and peripheral corneal thickness 2.0 mm from the scleral spur toward the corneal side (CT(P)). The ratio of CT2.5 to CT0 was calculated to obtain the hydrops resolving index (HyRI). RESULTS: The DM tear was visualized with UBM in all cases and slit-lamp microscopy in 9 of 14 eyes. The mean length of DM tears at presentation was 1.74 ± 0.77 µm. Patients with zone 3 corneal edema had a longer DM tear compared with patients with zone 2 corneal edema (1.27 ± 0.55 vs 2.02 ± 0.79 µm, respectively, P = 0.09). Significant positive correlations were seen between DM tear length and CT2.5 and CT(p) (r = 0.790, P = 0.020 and r = 0.766, P = 0.027, respectively). An intracameral gas bubble was seen abutting the edges of the tear in all cases. At the 6-week follow-up, the apposition of the DM and the overlying stroma occurred in all eyes, and resolution of epithelial edema and intrastromal cysts were seen in 11 of 13 cases (84.6%) and 12 of 13 cases (92.3%). The mean values of CT0, CT2.5, and CT(p) at presentation were 2359.69 ± 582.26 µm, 1911.15 ± 502.60 µm, and 1156.46 ± 275.77 µm, respectively, which decreased to 398.15 ± 31.65 µm (P = 0.0), 453.46 ± 68.45 µm (P = 0.0), and 638.00 ± 62.17 µm (P = 0.0), respectively. The mean HyRI showed a significant increase from 0.80 ± 0.05 at the time of presentation to 1.13 ± 0.12 (P = 0.03) at 3 months follow-up. CONCLUSIONS: Ultrasound biomicroscopy is a useful tool for quantitative and qualitative study of the morphologic features of acute hydrops. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Effect of a proparacaine 0.50%-sodium fluorescein 0.25% mix and contact ultrasound pachymetry on central and midperipheral corneal thickness measured by noncontact optical pachymetry.

PURPOSE: To assess the effect of a combination of proparacaine 0.50%-sodium fluorescein 0.25% and ultrasound (US) pachymetry on central and midperipheral corneal thickness. SETTING: School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom. DESIGN: Case series. METHOD: Topographic measurements of corneal thickness in healthy right eyes were obtained using a scanning-slit device (Orbscan IIz) and a Scheimpflug device (Pentacam) before and after application of proparacaine 0.50%-sodium fluorescein 0.25% and US pachymetry. Changes in corneal thickness in the center and 2.5 mm from the center in the temporal, nasal, inferior, and superior locations were assessed. RESULTS: The study evaluated 35 eyes. The scanning-slit and Scheimpflug devices recorded a small but statistically significant increase in corneal thickness at all locations (mean 4.9 ± 14.3 [SD] to 9.1 ± 11.7 µm; P<.05, paired t test). The cornea swelled uniformly across its diameter (scanning slit, P=.934; Scheimpflug, P=.654; analysis of variance); there was no statistically significant difference in the amount of swelling between the 2 devices (P>.05, t test). The 95% limits of agreement were broad (-10 to +30 µm), suggesting a large degree of interindividual variability. CONCLUSIONS: Ultrasound pachymetry combined with proparacaine 0.50%-sodium fluorescein 0.25% caused a small (<10 µm) but significant amount of corneal swelling on average. Because the effect on corneal thickness may be greater than -10 to +30 µm in individual cases, clinicians should avoid contact procedures before obtaining topographic maps of corneal thickness using scanning-slit and Scheimpflug devices.

Nonresolution of acute hydrops because of intrastromal migration of perfluoropropane gas.

PURPOSE: To report a case of nonresolution of acute hydrops despite treatment with intracameral perfluoropropane (C3F8) gas because of fish egging of the gas bubble. METHODS: An acute hydrops in a 25-year-old female patient with keratoconus was treated with intracameral injection of 0.15 mL of isoexpansile C3F8 (14%). RESULTS: Slit-lamp examination showed multiple small bubbles trapped inside the intrastromal cleft and persistence of corneal edema. CONCLUSION: Intraoperative fish egging of the C3F8 gas bubble can lead to intrastromal migration of the gas, which may prevent the closure of the intrastromal cleft and hence may impede the resolution of acute hydrops.

[Acute visual loss with bilateral corneal edema]. / Akuter Visusverlust mit beidseitigem Hornhautödem.

An 84-year-old woman presented with bilateral visual loss that had appeared 3 days previously. Split lamp examination showed bilateral corneal edema with normal intraocular pressure. The patient complained of headache and vomiting, and finally collapsed. Elevated levels of inflammation markers led to the suspicion of an inflammatory disease. After investigation for internal or neurological diseases, a biopsy of the temporal artery was performed. Giant cell arteritis (Horton's disease) was found, and steroid therapy was begun. The patient's general condition then improved.

[The effect of cataract and vitreoretinal surgery on central corneal thickness and corneal hysteresis]. / Einfluss der Katarakt- und Glaskörperchirurgie auf die Hornhautdicke und die Corneale Hysterese.

INTRODUCTION: Intraocular irrigating solutions remain for several hours beyond the actual time of surgery in the eye. The irrigating solution ought to resemble biochemically aqueous humor and vitreous and offer protection for sensitive structures of the eye, such as the corneal endothelium. Impairment of the corneal endothelium may lead to corneal oedema and biomechanical alterations of the cornea. PATIENTS AND METHODS: 54 eyes after pars-plana vitrectomy (PPV) in elective macular surgery were evaluated by measuring corneal thickness (CCT) using ultrasound pachymetry (20 MHz) and corneal hysteresis (CH) using the ocular response analyser (Reichert Ophthalmic Instruments, Buffalo, NY, USA). Measurements were performed not earlier than 2 weeks prior to surgery and 1 to 3 days after surgery. Results were compared to a control group (n = 39) and to 101 eyes after clear cornea cataract extraction (KAT). RESULTS: The two groups (PPV and KAT) did not differ with respect to age (p = 0.555). Corneal thickness has increased significantly in both groups (p