Retinal layers thickness changes following epiretinal membrane surgery.

PurposeTo evaluate the time course of changes in the thickness of retinal layers after epiretinal membrane (ERM) removal surgery.MethodsA retrospective cohort study of patients following surgery for idiopathic ERM. We used new specialized image analysis software to create a thickness map of each retinal layer and analyzed changes during one year follow-up. Healthy fellow eyes were used as negative controls and the retina prior to surgery as positive control.ResultsTwenty-one patients were included with a mean age of 68±13 years. Central macular thickness decreased steadily until 6 months after surgery (25% decrease, 516±76 to 386±73 µm, P<0.001) with no further decrease between 6 and 12 months (386±73 to 390±73 µm, P=0.291). The retinal nerve fiber layer (RNFL), and the ganglion cell and inner plexiform layer (GCIPL) were most affected (57%, P<0.001 and 27%, P=0.010, respectively). The thickest region showed a more abrupt decrease of 21% at first follow-up (504±61 to 399±58 µm, P=0.001) with subsequent decrements of about 3%. Prior to surgery all retinal layers were thicker in study eyes compared with healthy control eyes (6-63%, all P<0.05).ConclusionsFollowing ERM surgery, in the course of 6 months, the macula gradually becomes thinner after which a stable state is reached. All layers appear to be affected, with the RNFL and GCIPL impacted the most. Our results provide a unique view on how the thickness of different retinal layers changes following ERM surgery.

Intraocular pressure measurement after DSAEK by iCare, Goldmann applanation and dynamic contour tonometry: A comparative study.

PURPOSE: Corneal thickness inevitably increases following Descemet's stripping automated endothelial keratoplasty (DSAEK), owing to the addition of a donor graft. The current study compares different devices in assessing post-DSAEK intraocular pressure (IOP). METHODS: We compared IOP values measured by the Goldmann tonometry (GAT), iCare rebound tonometry (iCare) and Pascal dynamic contour tonometry (PDCT) in eyes following DSAEK. Agreement between measurements was calculated with correlation analysis and Bland-Altman plots. Effects of keratometry, central, thickness (CCT), endothelial cell density (ECD) and axial length on IOP measurements were assessed with Pearson's correlation. RESULTS: Twenty eyes of 20 patients (mean age 74.3±14.4, 14 females) post-DSAEK were included in this study. There was a high concordance between the IOP readings obtained by the three devices: a strong and significant correlation was found between GAT and PDCT (r=0.94, P<0.001) GAT and iCare (r=0.86, P<0.001) and iCare with PDCT (r=0.81, P<0.001). However, the iCare measurements were significantly and consistently lower than that obtained with GAT (ΔIOP=1.68±2.0, P=0.002, 95% CI: 0.7-2.6) and with PDCT (ΔIOP=1.61±2.5, P=0.01, 95% CI: 0.4-2.8). CCT, ECD, CCT, AXL, corneal curvature or astigmatism did not influence IOP measurement by any instrument. CONCLUSIONS: IOP measurement with three different techniques (applanation, rebound and dynamic contour) showed good correlations, despite an increased corneal thickness following DSAEK. However, the iCare, which is based on a rebound tonometry showed significant lower IOP then the two other methods. This should be taken into account when evaluating patients post DSAEK.

Inadvertent intravitreal gentamicin injection.

PURPOSE: To describe the management and consequences of an accidental injection of gentamicin in the vitreous. METHODS: A retinal detachment developed in a 70-year-old male. During a vitrectomy operation, gentamicin (20mg) was accidentally injected in to the eye. The surgeon immediately began vigorous lavage of the vitreal cavity with balanced salt solution. RESULTS: No toxic signs appeared after the operation, despite the devastating consequences described in previous reports. CONCLUSIONS: The immediate vigorous lavage may have reduced the concentration of the toxic material and its consequences.

Pulsatile ocular blood flow in diabetic retinopathy.

PURPOSE: To assess circulatory properties of eyes with progressive stages of diabetic retinopathy. METHODS: The intraocular pressure, pulse amplitude (PA) and pulsatile ocular blood flow (POBF) were measured with a pneumatonometer (OBF Labs UK Ltd). The eyes were grouped: (a) normal control, n = 26, (b) diabetes with no observable diabetic retinopathy (NDR), n = 18, (c) mild to moderate non-proliferative diabetic retinopathy (NPDR), n = 20, and (d) very severe pre-proliferative and proliferative diabetic retinopathy (PPDR/PDR), n = 12. RESULTS: The PA and POBF values were lower than normal values in the earliest stage (NDR). The POBF increased but was still below normal levels at the NPDR stage, and then increased to an above normal level in the PPDR/PDR stage of diabetic retinopathy. The PA was at normal levels in these later two stages. CONCLUSION: An initial decrease in pulsatile ocular blood flow is present with the onset of diabetes where no diabetic retinopathy has yet occurred. Subsequently, the pulsatile ocular blood flow increases with the severity of the retinopathy.

Total internal reflection of laser light in eyes filled with silicone oil.

BACKGROUND AND OBJECTIVES: This is the first report of clinical settings in which total internal reflection of laser light in eyes filled with silicone oil was observed. The authors analyze this phenomenon and outline the potential hazards it may present to patient, surgeon, and operating room personnel. MATERIALS AND METHODS: The authors observed significant reflection of laser light off the silicone-water interface both intraoperatively and in the clinic. The critical angle according to Snell's law (i.e., the angle at which total internal reflection occurs at the interface between silicone oil and vitreous) was calculated. The critical angle was found to be 71.9691 degrees(72 degrees). RESULTS: An analysis of each of the clinical conditions where this phenomenon was observed is presented. Clinical and surgical implications are discussed. CONCLUSIONS: The hazard of total internal reflection of laser light in eyes filled with silicone oil should be recognized by ophthalmologists to avoid possible complications. Techniques for overcoming and circumventing the difficulties resulting from this phenomenon are proposed.

Nucleus fragmentation in a scleral pocket for small incision extracapsular cataract extraction.

We present a technique for planned manual extracapsular cataract extraction (ECCE) incorporating a modification of mini-nuc ECCE in which the scleral tunnel is made wide enough to allow a nucleus of any size to settle in the tunnel. A 5.0 mm, inverted-V chevron incision is used in which the exposed part of the nucleus lodged in the scleral pocket can be manually picked and fragmented until it is small enough to be removed through the incision. The chevron incision is flexible enough to allow a medium-sized nucleus to be extracted without fragmentation and implantation of a rigid 6.0 mm poly(methyl methacrylate) lens. Vector analysis of preoperative and 3 month postoperative keratometric results in 30 patients showed that the surgically induced vector was 0.54 diopter (D) +/- 0.58 (SD). Mean reduction in astigmatism was 0.08 +/- 0.39 D. The sutureless technique is fast and safe, allows a nucleus of any size to be extracted through a constant size 5.0 mm incision, and results in minimal postoperative astigmatism.

Managing inferior zonule tears during manual extracapsular cataract extraction.

We describe a new technique for safely concluding manual extracapsular cataract extraction in the presence of a rupture of the interior zonules. A lens glide is inserted in the anterior chamber. The tip of the glide is placed in the inferior part of the capsular bag, pushing it toward the ciliary sulcus at 6 o'clock. The extraocular part of the glide is sutured to the sclera to prevent its displacement during manipulation of the eye. The glide spreads the rolled inferior capsule, allowing aspiration of retained cortical material and in-the-bag intraocular lens implantation. The glide is then removed. This technique was used in 12 eyes with pseudoexfoliation in which the complication occurred. No vitreous loss, lens displacement, or other intraoperative or postoperative complications were observed.

Role of blood components in ocular silicone oil emulsification. Studies on an in vitro model.

PURPOSE: To develop an in vitro model for silicone oil emulsification and to explore the blood components involved in this process. METHODS: The capacity of various blood components to support silicone oil (1000 CS) emulsification was studied by applying 0.5 ml oil on top of 0.5 ml saline containing various blood components. Each tube was sonicated for 150 seconds and centrifuged at 5000 g for 20 minutes. Three phases were noted in the tube: At the top was clear silicone oil, in the middle was emulsified silicone oil, and at the bottom was aqueous solution. The tubes were photographed, and the percentage of the phase length containing emulsified silicone oil (middle) of the total length of the three phases was calculated from the projected image of each tube. RESULTS: Emulsified silicone oil in plasma or serum was initiated after 100 seconds of sonication and quickly reached maximum (approximately 80%) at 120 seconds. The size of these oil droplets prepared in vitro was 0.0467 +/- 0.028 mm, closely resembling that observed in oil samples removed from a patient's anterior chamber (0.038 +/- 0.018 mm). Under these conditions, silicone oil emulsified in the presence of whole blood cells occurred only at a concentration of 120 micrograms protein/ml; in the presence of red blood cell membranes, it occurred at a concentration of 60 micrograms protein/ml. Lipoprotein-deficient serum failed to support emulsification; however, samples of high-density lipoprotein and low-density lipoprotein supported this process. Purified high-density lipoprotein-apolipoproteins supported oil emulsification. The addition of phosphatidylcholine further enhanced this process, but phosphatidylcholine alone failed to support emulsification. CONCLUSIONS: A simple and fast in vitro model to study factors affecting silicone oil emulsification was developed. Using this model, red blood cell membranes, plasma lipoproteins, and purified HDL-apolipoproteins supported silicone oil emulsification. Lipids did not, but they had the capacity to enhance the apolipoprotein-supported emulsification.

Safe method for cleaning the posterior lens capsule.

Cleaning the posterior capsule is an important step in cataract microsurgery to prevent early postoperative visual impairment. A simple method for cleaning posterior lens capsule opacities during extracapsular cataract extraction is described. A straight 20-gauge cannula with a 0.3 mm anterior aspiration port, attached to a syringe with the piston removed, allows safe polishing in a deep anterior chamber. The described procedure has been safely performed in more than 300 operations.

Angiogenic activity of vitreous extract obtained from rabbit eyes with endotoxin-induced uveitis.

The effect of rabbit vitreous with endotoxin-induced uveitis was investigated for its role in the modulation of rat corneal neovascularization (NV). Elvax pellets implanted into at cornea contained either uveitic vitreous, intact vitreous or Elvax alone. The latter two kinds of pellets did not elicit NV. Uveitic vitreous pellets caused, in 100% of eyes, a persistent NV with maximal growth on the 10th day post implantation. Prostaglandin E2 and leukotriene B4 levels in the uveitic rabbit vitreous at 36 h postendotoxin injection were 7- and 5-fold higher than baseline, respectively. Histopathologically, the neovascularized cornea showed a significant inflammatory reaction attributable to the uveitic vitreous extract.

Methylcellulose as a contact lens irrigant when silicone oil is used in vitreoretinal surgery.

When silicone oil, a hydrophobic agent, is injected into the vitreous cavity during the course of vitrectomy operations, often some escapes outside the eye, and a mixture of oil and water forms under the infusion contact lens, markedly interfering with visibility. We found that a viscous solution of methylcellulose 1.75% in saline used as the infusion contact lens irrigant, instead of a saline solution alone, can prevent silicone oil from entering under the contact lens, thus avoiding this difficulty.

Long-term follow up of accidental parafoveal laser burns.

The findings after 12 years of follow-up evaluation of 2 patients who sustained accidental parafoveal and juxtafoveal Nd:YAG laser injuries are reported. In both cases, the fovea was not destroyed by the initial insult and early scar formation. Both cases demonstrated, after more than a decade, minimal visual deficit without significant late complications. In spite of early decrease in visual performance, the long-term prognosis for Q-switched Nd:YAG laser retinal lesions in which the fovea was not directly involved in the injury or its repair mechanisms is relatively benign.

Cataract extraction in eyes filled with silicone oil.

A surgical technique for cataract extraction in eyes filled with silicone oil was developed that has two major objectives: removal of the entire cataractous lens and complete preservation of the silicone oil volume. A regular extracapsular cataract extraction or phacoemulsification is performed, and the incision is closed with the final sutures. All steps are performed under continuous positive pressure achieved with an anterior chamber maintainer connected to a bottle of balanced saline solution. An inferior basal iridectomy is created with a vitrectomy probe, and the posterior capsule is then slowly pulled out through the limbal incision with intraocular forceps, again under positive pressure, in an eye that is actually a closed system, without any loss of silicone. This step results in transformation of the extracapsular cataract extraction condition into an intracapsular cataract extraction condition. The described technique was successfully performed in nine eyes. In the younger patients, the whole procedure was completed through two very small limbal openings.

Self-inflicted ocular mutilation in the pediatric age group.

Three mentally retarded children with severe self-inflicted ocular injuries are presented. All three suffered from severe ocular injuries including retinal detachment resulting in progressive visual loss and even blindness. Self-inflicted injuries to the eyes, including self enucleation, is an extremely uncommon form of behavior, rarely encountered by pediatricians. The risk of ocular morbidity is high if the diagnosis is overlooked. Technical advances in ophthalmology permit much improvement in some formerly hopeless cases of ocular self-mutilation, but there is still no accurate method to repair destroyed retinal or nervous tissue. Early identification of patients at risk of ocular self-mutilation is essential in order to prevent or minimize such severe ocular injuries.

Continuous control of intraocular pressure in pseudophakic retinal detachment surgery.

We describe a method for continuous control of intraocular pressure in pseudophakic retinal detachment surgery done shortly after extracapsular cataract extraction and posterior chamber intraocular lens implantation. The system consists of a special needle inserted into the anterior chamber through the corneal limbus. The needle is attached by a regular intravenous administration set to an infusion bag. This allows fluids to exit the eye when the eyeball is compressed and to return to the eye when pressure on the eye is released. The presence of an intact posterior capsule and an intraocular lens do not impose a significant barrier to the passage of fluids between the anterior chamber and the vitreous cavity. Using this technique, intraocular pressure can be stabilized throughout the operation. The implementation of this system is demonstrated by a case report.

Transient fluorescein leakage simulating subretinal membrane: a diagnostic dilemma.

A 68-year-old woman with blurred vision had a foveal spot of fluorescein leakage that later was found to be a transient leakage. The clinical picture resembled central serous chorioretinopathy, a rare diagnosis in older patients. Other possible diagnoses (e.g., subretinal neovascular membrane or epiretinal membrane) are discussed as is the need for laser treatment.

[Treatment of retinal detachment with intraocular expandable gas injection].

The injection of expandable gas into the vitreous is a new method for treating retinal detachment. The injected gas bubble seals the retinal break and allows absorption of subretinal fluid. In 12 patients, in all eyes treated by injection of sulfur hexafluoride, the detached retina became reattached. In 3 eyes (25%) detachment recurred. To achieve attachment again, both vitrectomy and the circling band operation were performed in 2 of them, and only the latter operation in the third. Risk factors for redetachment included detachment of the macula, retinal detachment larger than 5-o'clock-hours, and pseudophakia. Proper selection of patients for gas injection is most important.