Songhomitra Panda-Jonas

Ophthalmoscopic Evaluation of the Optic Nerve Head

Optic nerve diseases, such as the glaucomas, lead to changes in the intrapapillary and parapapillary region of the optic nerve head. These changes can be described by the following variables: size and shape of the optic disk; size, shape, and pallor of the neuroretinal rim; size of the optic cup in relation to the area of the disk; configuration and depth of the optic cup; ratios of cup-to-disk diameter and cup-to-disk area; position of the exit of the central retinal vessel trunk on the lamina cribrosa surface; presence and location of splinter-shaped hemorrhages; occurrence, size, configuration, and location of parapapillary chorioretinal atrophy; diffuse and/or focal decrease of the diameter of the retinal arterioles; and visibility of the retinal nerve fiber layer (RNFL). These variables can be assessed semiquantitively by ophthalmoscopy without applying sophisticated techniques. For the early detection of glaucomatous optic nerve damage in ocular hypertensive eyes before the development of visual field loss, the most important variables are neuroretinal rim shape, optic cup size in relation to optic disk size, diffusely or segmentally decreased visibility of the RNFL, occurrence of localized RNFL defects, and presence of disk hemorrhages.

Intravitreal injection of crystalline cortisone as adjunctive treatment of proliferative vitreoretinopathy

AIM To report on clinical outcome and complications of intravitreal injection of crystalline cortisone in patients undergoing pars plana vitrectomy for treatment of proliferative vitreoretinopathy. METHODS The study included all 16 patients who underwent pars plana vitrectomy for treatment of proliferative vitreoretinopathy, who received an intravitreal injection of 10–20 mg crystalline triamcinolone acetonide at the end of surgery, and who were operated on by the same surgeon. Most of the vehicle of the solution containing the cortisone crystals was removed before performing the injection. Mean follow up time was 1.64 (SD 2.15) months (median 1.23 months; range 0.20–9.20 months). The study group was compared with a control group which consisted of 144 patients undergoing pars plana vitrectomy for proliferative vitreoretinopathy performed by the same surgeon. RESULTS In the study group compared with the control group, intraocular inflammation, as estimated clinically by slit lamp biomicroscopy, was lower, appearance of the fundus upon ophthalmoscopy in the first postoperative week was clearer, and postoperative pain in the first two postoperative days was reduced. Intraocular pressure measured at the end of the first postoperative week did not vary significantly between the groups. A pseudohypopyon consisting of cortisone crystals in the inferior anterior chamber angle was detected in one patient. Postoperative infectious endophthalmitis was not encountered. CONCLUSIONS This pilot study suggests that intravitreal injection of crystalline cortisone with most of the vehicle removed is not toxic to intraocular structures, reduces postoperative intraocular inflammation, and may be a potentially useful additional tool in the treatment of proliferative vitreoretinopathy.

Intravitreal injection of crystalline cortisone as adjunctive treatment of proliferative diabetic retinopathy.

PURPOSE To report the clinical outcome and complications of intravitreal injections of crystalline cortisone in patients undergoing pars plana vitrectomy for treatment of proliferative diabetic retinopathy. METHODS The prospective, interventional case series study included 29 consecutive patients (29 eyes) who underwent pars plana vitrectomy for treatment of complicated proliferative diabetic retinopathy associated with central retinal traction detachment. All patients received an intravitreal injection of 15 to 20 mg of crystalline triamcinolone acetonide at the end of surgery, and were operated on by the same surgeon. Mean follow-up time was 1.4 +/- 1.1 months (median, 1 month; range, 0.30 to 4.9 months). RESULTS At the end of the follow-up period, the retina was attached in 26 of the 29 patients (89.7%). In three of the 29 patients (10.3%), a retinal redetachment had occurred. None of the patients developed iris neovascularization, and the iris neovascularization, present preoperatively in 12 patients, slightly to markedly regressed in all 12 patients. Preoperative and postoperative intraocular pressure values (P =.72) and blood glucose measurements did not vary significantly. A pseudohypopyon consisting of cortisone crystals in the inferior anterior chamber angle was detected in one patient and resolved spontaneously within 4 days. CONCLUSIONS The present clinical study suggests that intravitreal injection of crystalline cortisone with most of the vehicle removed seems to be well tolerated by eyes undergoing pars plana vitrectomy for treatment of complicated diabetic proliferative retinopathy. In view of the antiphlogistic and antiproliferative effect of cortisone, future randomized clinical trials may be indicated to investigate further the role of intravitreal injection of crystalline cortisone in the treatment of proliferative diabetic retinopathy.

Retinal Pigment Epithelial Cell Count, Distribution, and Correlations in Normal Human Eyes

PURPOSE To determine the number of the retinal pigment epithelial cells, their regional distribution, and correlations with general variables in normal human eyes. METHODS We examined 53 normal human donor eyes from individuals with a mean age of 58.6 +/- 18.8 years and an axial length of less than 27 mm. After opening the globes by a 16-mm corneoscleral trephination, up to 25 biopsy specimens of the retina and retinal pigment epithelium were obtained in four meridians. The retinal pigment epithelial cells and the retinal photoreceptors were counted on photographs taken from the apical retinal pigment epithelial surface and the inner photoreceptor segments. RESULTS Total number of the retinal pigment epithelial cells was 3,556,290 +/- 490,700 (mean +/- S.D.; range, 2,130,500 to 4,653,200), and it was positively correlated with the number of rods and cones, the total area of the retina, the optic disk size, and the retinal pigment epithelial cell density but was independent of gender. The retinal pigment epithelial cell density decreased significantly (P < .001) from the fovea (4,220 +/- 727 cells/mm2) to the midperiphery (3,002 +/- 460 cells/mm2) and to the outer peripheral fundus regions (1,600 +/- 411 cells/mm2). In the retinal periphery, the retinal pigment epithelial cell density was the highest (P < .01) in the nasal fundus region compared with any other fundus quadrant. The retinal pigment epithelial cell density decreased by about 0.3% per year with increasing age. CONCLUSIONS These data on the quantitative anatomy of the retinal pigment epithelium may be important for physiology and pathophysiology of the visual process, especially in evaluating the effects of aging.

Retinal Photoreceptor Density Decreases with Age

PURPOSE To evaluate the effect of age on the density of retinal photoreceptors in humans. METHODS Fifty-five normal eyes from human donors, with a mean age of 58.7 +/- 19.1 years and an axial length of less than 27 mm, were examined. After opening of the globes by a 16-mm corneoscleral trephination, 25 retinal tissue samples were obtained in four meridians. The photoreceptors were counted on photographs taken from the photoreceptor inner segments after sonographic removal of the outer segments. The cones in the foveal center could not be evaluated. RESULTS Outside the foveal center, the photoreceptor density decreased significantly with increasing age. In absolute and relative terms, the decline was more marked for the rods (mean rod loss, 236 +/- 63 cells or 0.37% +/- 0.10%/mm2 and year of a mean density of 62.987 rods/mm2) than for the cones (mean cone loss, 5.90 +/- 0.68 cells or 0.18% +/- 0.02%/mm2 and year of a mean density of 3320 +/- 578 cones/mm2). For both cones and rods, the cell loss was more marked at an eccentricity of approximately 5-8 mm than in the retinal periphery at an eccentricity of 14 to 20 mm. There were no significant differences between the superior, inferior, temporal, or nasal meridian nor between women and men. CONCLUSIONS The photoreceptors decrease in density with increasing age. The annual cell loss of approximately 0.2% to 0.4% is similar to the age-related loss of retinal ganglion cells and pigment epithelium cells. The decline in photoreceptor count affects more rods than cones. It does not prefer special age groups. It is more pronounced at an eccentricity of 5 to 8 mm than in the retinal periphery at an eccentricity of more than 14 mm. It may be important for an age-related decrease in visual functions and for diseases affecting the photoreceptors in elderly patients.

Regression of neovascular iris vessels by intravitreal injection of crystalline cortisone.

PurposeTo report the clinical outcome of patients who received an intravitreal injection of crystalline triamcinolone acetonide as treatment of neovascular glaucoma. Patients and MethodsThe study included 14 eyes of 14 patients with secondary neovascular glaucoma attributable to proliferative diabetic retinopathy (n = 9) or ischemic central retinal vein occlusion (n = 5). All patients received an intravitreal injection of 20 mg of crystalline triamcinolone acetonide as the only procedure (n = 4) or in combination with additional procedures, such as goniosynechiolysis (n = 1), phacoemulsification and intraocular lens implantation (n = 2), or transscleral peripheral retinal cryocoagulation (n = 7). Mean follow-up time was 3.10 ± 2.40 months (median, 3.5 months; range, 0.50–5.7 months). A goniosynechiolysis was carried out in those patients in whom the anterior chamber was circumferentially closed. ResultsAfter surgery, including the first days after surgery, the patients were nearly pain-free. Intraocular pressure was significantly (P <0.01) reduced from 33.4 ± 14.5 mm Hg before surgery to 20.7 ± 8.2 mm Hg at the end of the follow-up period. Postoperative visual acuity (mean, 0.09 ± 0.07; median, 0.10; range, finger counting to 0.25) was slightly but not significantly (P = 0.31) better than the preoperative values. Degree of rubeosis iridis decreased significantly (P = 0.02) from 2.6 ± 1.3 relative units to 1.3 ± 1.2 relative units. When considering only the four patients for whom the intraocular cortisone injection was the only procedure performed, mean intraocular pressure decreased from 26.5 ± 12.1 mm Hg to 21.75 ± 11.3 mm Hg. ConclusionsIntravitreal injection of crystalline cortisone with most of the vehicle removed may be a potentially useful additional tool in the treatment of neovascular glaucoma.

Parapapillary Atrophy: Histological Gamma Zone and Delta Zone

Background To examine histomorphometrically the parapapillary region in human eyes. Methodology/Principal Findings The histomorphometric study included 65 human globes (axial length:21–37 mm). On anterior-posterior histological sections, we measured the distance Bruchs membrane end (BME)-optic nerve margin (“Gamma zone”), BME-retinal pigment epithelium (RPE) (“Beta zone”), BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer. “Delta zone” was defined as part of gamma zone in which blood vessels of at least 50 µm diameter were not present over a length of >300 µm. Beta zone (mean length:0.35±0.52 mm) was significantly (P = 0.01) larger in the glaucoma group than in the non-glaucomatous group. It was not significantly (P = 0.28) associated with axial length. Beta zone was significantly (P = 0.004) larger than the region with occluded choriocapillaris. Gamma zone (mean length:0.63±1.25 mm) was associated with axial length (P<0.001;r2 = 0.73) with an increase starting at an axial length of 26.5 mm. It was not significantly (P = 0.24) associated with glaucomatous optic neuropathy. Delta zone (present only in eyes with axial length of ≥27 mm) was associated with axial length (P = 0.001) and scleral flange length (P<0.001) but not with glaucoma (P = 0.73). Conclusions/Significance Parapapillary gamma zone (peripapillary sclera without overlying choroid, Bruchs membrane and deep retinal layers) was related with axial globe elongation and was independent of glaucoma. Delta zone (no blood vessels >50 µm diameter within gamma zone) was present only in highly axially elongated globes and was not related with glaucoma. Beta zone (Bruchs membrane without RPE) was correlated with glaucoma but not with globe elongation. Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.

Scleral Thickness in Human Eyes

Purpose To obtain information about scleral thickness in different ocular regions and its associations. Methods The histomorphometric study included 238 human globes which had been enucleated because of choroidal melanomas or due to secondary angle-closure glaucoma. Using light microscopy, anterior-posterior pupil-optic nerve sections were measured. Results In the non-axially elongated group (axial length ≤26 mm), scleral thickness decreased from the limbus (0.50±0.11 mm) to the ora serrata (0.43±0.14 mm) and the equator (0.42±0.15 mm), and then increased to the midpoint between posterior pole and equator (0.65±0.15 mm) and to the posterior pole (0.94±0.18 mm), from where it decreased to the peri-optic nerve region (0.86±0.21 mm) and finally the peripapillary scleral flange (0.39±0.09 mm). Scleral thickness was significantly lower in the axially elongated group (axial length >26 mm) than in the non-axially elongated group for measurements taken at and posterior to the equator. Scleral thickness measurements of the posterior pole and of the peripapillary scleral flange were correlated with lamina cribrosa thickness measurements. Scleral thickness measurements at any location of examination were not significantly (all P>0.10) correlated with corneal thickness measurements. Scleral thickness was statistically independent of age, gender and presence of glaucoma. Conclusions In non-axially elongated eyes, the sclera was thickest at the posterior pole, followed by the peri-optic nerve region, the midpoint between posterior pole and equator, the limbus, the ora serrata, the equator and finally the peripapillary scleral flange. In axially elongated eyes, scleral thinning occurred at and posterior to the equator, being more marked closer to the posterior pole and the longer the axial length was. Within the anterior and posterior segment respectively, scleral thickness measurements were correlated with each other. Posterior scleral thickness was correlated with lamina cribrosa thickness. Scleral thickness measurements at any location of examination were not significantly correlated with corneal thickness or with age, gender and presence of absolute secondary angler-closure glaucoma.

Retinal Photoreceptor Count, Retinal Surface Area, and Optic Disc Size in Normal Human Eyes

PURPOSE The optic disc area of normal human eyes shows an interindividual variability of 1:7. This study evaluated whether the variation in the optic nerve head size is correlated with a variability in the retinal photoreceptor count and the retinal surface area. METHODS Forty-six normal human donor eyes with an axial length of less than 26 mm were examined. The corneoscleral button, lens, and vitreous body were removed. The remaining cup of the eye was cut into orange slice-like pieces. Up to 25 retinal biopsies were taken from areas arranged in increasing distance from and concentric to the fovea. The photoreceptor outer segments were sonographically removed. The photoreceptor inner segments were counted on photographs taken from the outer side of the retina. RESULTS The count of the rods (mean +/- standard deviation: 57,447,000 +/- 10,481,000), the count of the cones (3,246,000 +/- 618,000), the optic disc size, and the retinal surface area (1204 +/- 184 mm2) were significantly (P < 0.05) and positively correlated with each other. CONCLUSIONS The results indicate that eyes with large optic nerve heads as compared with eyes with small optic discs may have a higher count of rods and cones and a larger retinal surface area. It corresponds with the positive correlation between the optic nerve fiber count and the optic disc size. Taking into account a loss of photoreceptors in glaucoma as recently reported, it may point toward a higher anatomic reserve capacity in glaucomatous eyes with large optic discs than in eyes with small optic nerve heads.

Histology of the Parapapillary Region in High Myopia

PURPOSE To examine histomorphometrically the parapapillary region in highly myopic eyes. DESIGN Retrospective laboratory investigation. METHODS We examined a highly myopic glaucomatous group (36 human globes; axial length >26.5 mm) and a non-highly myopic group (28 globes with secondary angle-closure glaucoma; 17 eyes with malignant choroidal melanoma). Using light microscopy, pupil-optic nerve sections were assessed. RESULTS The length of the scleral flange (sclera between optic nerve border and optic nerve dura mater) increased with axial length (P < .001; correlation coefficient r = 0.70) and decreased with its thickness (P < .001; r = 0.75). In all highly myopic eyes (n = 15) with a distance of >0.5 mm between optic nerve border and beginning of Bruch membrane, the parapapillary region consisted of an elongated parapapillary scleral flange associated with a scleral flange thinning and a retrobulbar cerebrospinal fluid space extended into the retroparapapillary region. The parapapillary retina was composed of retinal nerve fiber layer (or its remnants) only, without elements of any other retinal layer, without underlying Bruch membrane or choroid. These histologic features were not detected in any of the non-highly myopic eyes. CONCLUSIONS Since parapapillary scleral thickness influences the lamina cribrosa biomechanics, the findings may partially explain the increased glaucoma susceptibility in highly myopic eyes. The implications of an absence of Bruch membrane and choroid in the highly myopic parapapillary region, and the implications of the retrobulbar parapapillary extension of the cerebrospinal spinal fluid space for the pathophysiology of the optic nerve head, have to be elucidated.