Erosion and intrusion of silicone rubber scleral buckle. Presentation and management.

OBJECTIVE: To describe the clinical presentation and management of erosion and intrusion of silicone rubber implants that are used in scleral buckling procedures for the treatment of retinal detachment. METHODS: The authors identified four patients from their practices during the last 20 years (1978-1998) who had erosion or intrusion of silicone rubber scleral buckles that were used to manage retinal detachment. Approximately 4400 scleral buckling procedures were performed during this period. A retrospective review of the medical records of all patients was performed. Factors that influenced management decisions concerning the intruding buckle are emphasized. RESULTS: All four patients had myopia. The interval between placement of the scleral buckle and development of intrusion ranged from 1 to 20 years. The buckles were intrascleral in three cases and episcleral in one. Recurrent detachment and vitreous hemorrhage were indications for surgical intervention in three cases. After the surgical removal of buckling elements, visual acuity stabilized in all patients and the retina remained attached in all cases. CONCLUSIONS: Erosion and intrusion of scleral buckle are rare complications of scleral buckling procedures. The intruding buckle may be left intact unless there is significant threat to the integrity of ocular structures, recurrent detachment, or hemorrhage. Manipulation of the encircling band or buckle does not necessarily alter the visual acuity or the status of the retina.

Complications associated with posterior staphyloma.

Macular degeneration can result in legal blindness among those with progressive myopia and posterior staphyloma. Programmed photoreceptor death, apoptosis, is operative in some. Electrophysiologic and psychophysiologic techniques can permit detection of functional abnormalities before lesions become clinically apparent. Macular choroidal neovascularization occurs more often in those with moderate staphyloma than in those with advanced atrophy in the posterior pole. Indocyanine green angiography is improving our understanding of this complication, which has been correlated with an increased number of posterior choroidal drainage systems. One study suggests that surgical extirpation of the neovascular network may be beneficial in some, but the role of scleroplasty procedures in prevention remains uncertain. Experimental myopia modeling continues apace, but specific molecular pathways and their genomic control are yet to be elucidated. Clinically, clear lens extraction and biphakia techniques are under investigation to offer refractive relief to the severely myopic patients who are not candidates for current keratorefractive methods.

Macular complications associated with posterior staphyloma.

PURPOSE: To report macular abnormalities associated with posterior staphyloma in eyes with myopia. METHODS: In a retrospective study, we surveyed 116 eyes of 58 patients with myopic refractions. Myopic fundus abnormalities are related to clinically quantified posterior staphyloma formation. RESULTS: A posterior staphyloma was present in 88 (75.9%) of 116 eyes with myopic refractions of -3 diopters or more. Best-corrected visual acuity was decreased among eyes in all staphyloma grades. Eyes with the shallowest staphyloma depth (grade 1) displayed the largest drop in visual acuity as well as the greatest frequency of choroidal neovascular membranes and hemorrhages. A linear relationship was observed between staphyloma grade and conus formation (P = .001), retinal pigment epithelial defects (P = .0001), lacquer cracks (P = .0001), and chorioretinal atrophy (P = .001). All these variables were increased in staphylomatous eyes. A significant difference in means by staphyloma grade was observed for myopic refractive error (P = .001), axial length (P = .001), and best-corrected visual acuity (logMAR, P = .0001). CONCLUSIONS: There was an unexpected high frequency of choroidal neovascular membranes, hemorrhage, and poor best-corrected visual acuity in the lower staphyloma categories. This suggests that the development of a choroidal neovascular membrane requires relative preservation of the choriocapillaris as present in eyes with less advanced stages of posterior staphyloma formation.

Mutations in the tissue inhibitor of metalloproteinases-3 (TIMP3) in patients with Sorsby's fundus dystrophy.

The hereditary macular dystrophies are progressive degenerations of the central retina and contribute significantly to irreversible visual loss in developed countries. Among these disorders, Sorsby's fundus dystrophy (SFD), an autosomal dominant condition, provides an excellent mendelian model for the study of the genetically complex age-related macular degeneration (AMD), the most common maculopathy in the elderly. Recently, we mapped the SFD locus to 22q13-qter. This same region contains the gene for tissue inhibitor of metalloproteinases-3 (TIMP3), which is known to play a pivotal role in extracellular matrix remodeling. We have now identified point mutations in the TIMP3 gene in affected members of two SFD pedigrees. These mutations are predicted to disrupt the tertiary structure and thus the functional properties of the mature protein.

Retinal function in birdshot retinochoroidopathy.

The electroretinograms (ERGs) of 15 patients with birdshot retinochoroidopathy varied from super-normal to non-recordable, depending upon the severity and the stage of the disease. The abnormal ERGs were characterized by a disproportionate decrease of the b-wave amplitude compared with the a-wave amplitude, demonstrating the negative (-) type response. This distinct ERG pattern has not been observed in any other type of uveitis or chorioretinitis, and appears specific to birdshot retinochoroidopathy. ERG findings indicate that in birdshot retinochoroidopathy the neural layers of the retina are more diffusely and severely involved than the receptor-retinal pigment epithelium-choroid complex. In the most advanced stage, the patients becomes night blind with a non-recordable ERG, a situation that is essentially the same as retinitis pigmentosa, except that pigmentation is conspicuously absent in the fundus.

Hereditary hemorrhagic macular dystrophy.

We treated two brothers who had a hemorrhagic macular lesion in one eye; a similar problem affected the fellow eye of both patients within eight months. Generalized fine granularity of the retinal pigment epithelium and peripheral iris transillumination defects were observed in both siblings. A study of the family suggested that the disorder was dominantly inherited and probably was Sorsby's pseudoinflammatory macular dystrophy. The macular lesions in one brother were treated by argon green laser photocoagulation and in the other brother by krypton red laser photocoagulation. Although the brother treated by krypton red laser photocoagulation attained better final visual function, additional differences in treatment methods also may have contributed to the final outcome.

Prevalence of lattice degeneration and its relation to axial length in severe myopia.

We studied 436 eyes of 218 patients with myopia of -6.00 diopters or more in both eyes. Of 218 patients, 72 (33.0%) had lattice degeneration of the retina. Among these 72 patients, lattice lesions were uniocular in 39 (54.2%) and binocular in 33 (45.8%). Of 105 males, 33 (31.4%) had lattice degeneration; of 113 females, 39 (34.5%) had lattice degeneration. Contrary to previously published data, we found an inverse relationship between axial length and the prevalence of lattice degeneration in severely myopic eyes. The greatest prevalence of lattice degeneration (63 of 154 eyes, 40.9%) was found in eyes with an axial length of 26.0 to 26.9 mm (-6.00 to -8.70 diopters), and the least prevalence of lattice degeneration (five of 71 eyes, 7.0%) was found in eyes with an axial length of 32.0 mm (-24.00 diopters) or greater. This may explain the observation that retinal detachment after cataract surgery has been noted more commonly among patients with moderate than severe myopia.

Distinctive cataract in the Stickler syndrome.

We determined the clinical characteristics of cataract in 133 patients with the Stickler syndrome. Cataracts of various types or aphakia were found in 115 of 231 eyes (49.8%) studied. The most frequent and distinctive lesions, described as wedge and fleck cataracts, accounted for 40 of the 93 cataracts (43.0%) observed. These distinctive opacities may serve as a clinical marker for the Stickler syndrome and facilitate early diagnosis.

Refractive surgery: psychophysical considerations in progressive myopia.

There is a trend towards recommending refractive surgery for young patients with high degrees of progressive myopia. Although many can benefit from certain procedures, staphylomatous eyes present unique impediments to normal visual acuity, visual field, binocularity and stereopsis. They are also prone to premature cataract formation, glaucoma and retinal detachment. An initially good result can be destroyed by continued scleral expansion with posterior retinal degeneration. A review of these limitations should be included in discussions with patients considering refractive surgery.

Progressive myopia and intraocular pressure: what is the linkage? A literature review.

Progressive myopia may result from an inherited biomechanical weakness of the sclera that allows it to stretch (creep) in response to stress. Increased intraocular pressure could be the mediator of stress produced by the inclined head position and the accommodation/convergence aspects of near work. This paper reviews data that relate to this hypothesis including work on sclera, intraocular pressure, animal models of myopia, and attempts at human treatment. Although the weight of evidence appears to support the proposed notion, no firm conclusion can be drawn due to imperfections in the design of prior studies. A future research agenda is proposed, including a controlled clinical trial of pharmacologically sustained ocular hypotension in young progressive myopes.

Transient visual loss in ornithine transcarbamoylase deficiency.

We examined a 32-year-old, previously healthy man who developed episodic bilateral visual impairment and confusion. Coincident hyperammonemia led to the diagnosis of ornithine transcarbamoylase deficiency, which was established by enzymatic analysis of a liver biopsy specimen. The available data were insufficient to determine if the metabolic derangement impaired vision at the level of the optic nerves or at the cerebral level.

Choroidal neovascularization in degenerative myopia: role of laser photocoagulation.

Laser photocoagulation of extrafoveal choroidal new vessels was performed in 19 eyes with degenerative myopia. Sixteen eyes required only one treatment. Three eyes required more than one because of incomplete closure of the new vessels after the first treatment. Choroidal new vessel formation did not recur during the post-treatment follow-up period (average 29.2 months), and a dry, atrophic photocoagulation scar was achieved in all eyes. Visual acuity improved in only two eyes (11%), stabilized in four eyes (21%), and deteriorated in 13 eyes (68%). All except two eyes showed spontaneous progressive enlargement of the atrophic photocoagulation scar, which worsened visual acuity in 13 eyes (68%).

Ocular coloboma associated with a solitary maxillary central incisor and growth failure: manifestations of holoprosencephaly.

A one-year-old boy presented with findings of ocular colobomas and staphylomas in both eyes. He also had a single central incisor and growth failure. His mother had hyposmia. We think that the patient and his mother represent the mild end of the spectrum of autosomal dominant holoprosencephaly.

Myopic cracks, angioid streaks, and traumatic tears in Bruch's membrane.

We studied the pattern of break formation in 60 eyes with myopic lacquer cracks, angioid streaks, or traumatic tears in Bruch's membrane, using a graphics composition technique and computer analysis of digitized images. Lacquer cracks were found in a reticular distribution within a posterior staphyloma; angioid streaks occurred in a spider-web configuration centered on the optic nerve; traumatic tears were characteristically curved, perineural, and eccentric temporally. The specific break patterns imply the operation of biomechanical forces.

Giant cysts of the conjunctiva following scleral buckling.

Four patients developed giant conjunctival cysts following scleral buckling for retinal detachment. Histologically these cysts showed a core of fibrous tissue lined by stratified, non-keratinizing epithelium and with goblet cells. They probably arose from inadvertent implantation of epithelium during surgery. In three cases the cysts were surgically excised without recurrence. Alternate modes of therapy are discussed.

Transmission electron microscopic observations of vitreous abnormalities in retinitis pigmentosa.

Ultrastructural studies of six vitreous biopsy specimens obtained during cataract surgery on patients with retinitis pigmentosa showed four types of cells. These were ocular pigment epithelium, uveal melanocytes, retinal astrocytes, and macrophage-like cells. The fibrous astrocytes displayed plump cell bodies, large nuclei, and numerous intracytoplasmic filaments. The pigment epithelial cells and uveal melanocytes were round to cuboidal and were heavily pigmented. Macrophage-like cells demonstrated round cell bodies, inclusions of glycogen, and long processes extending from the cell membrane. Also identified in the vitreous material were loose pigment granules. In contrast, vitreous from the control group showed occasional macrophages and loose pigment. These findings explained the clinical observation of material within the vitreous of patients with retinitis pigmentosa.

Natural history of choroidal neovascularization in degenerative myopia.

We studied 354 eyes with myopic chorioretinal degeneration by means of standard clinical evaluation and fluorescein angiography. The eyes were classified on the basis of the degree of chorioretinal degeneration found in the posterior pole. Lacquer cracks (breaks in Bruch's membrane) were noted in 82% of the 149 eyes with choroidal neovascular membranes (CNM) and in 96% of the 58 eyes with isolated subretinal hemorrhages. These hemorrhages were reabsorbed without adverse visual sequelae in 32 eyes that were followed; in 14 of these eyes that were followed closely, the average time of reabsorption was 6.4 weeks. Seventy eyes with CNM were followed for an average of 40.9 months. In 96% of these eyes the CNM remained stable or regressed, leaving an atrophic, nonexudative scar. This study indicates that CNM in degenerative myopia is usually self-limited.