Successful Treatment of Corneal Opacification with Associated Thickened Epithelium by Simple Peeling: Acquired Corneal Subepithelial Hypertrophy (ACSH).

PURPOSE: To study clinical and histopathological findings of corneal opacification caused by thickened epithelium leading to reduced vision and topographical changes and to evaluate the outcome of its removal. METHODS: Twelve patients (17 eyes) with central, paracentral or peripheral corneal opacification were reviewed to obtain their visual acuity, describe their slit lamp (SL) appearance (depth, extent and density) and document their topographic changes before and after peeling of the epithelium under SL or surgical removal under the microscope. Specimens of six cases were available for histopathological examination and immunohistochemical staining. RESULTS: Most of the eye opacifications were secondary to corneal procedures in 10 [Penetrating keratoplasty (PKP) in 7 for congenital glaucoma, keratoconus or adherent leukoma - usually over graft-host junction -, Photorefractive keratectomy (PRK) in 2 and Phototherapeutic keratectomy in one], chronic inflammation following trachoma or non-specific causes (3), and herpetic scar (1). Three cases were considered to be idiopathic. All cases presented with decreased vision, astigmatism or changes in topography or refraction. Their vision, clinical symptoms and topography improved after treatment. Histopathologically, all six cases shared findings that are similar to what have been described as peripheral hypertrophic subepithelial corneal degeneration (PHSCD) rather than Salzmann's nodular degeneration. None of the cases showed inflammation or subepithelial pannus formation in the excised tissue. However, our cases did not fit into the diagnosis of PHSCD because of the location of the corneal opacification (being peripheral in 41% of the corneas, the presence of underlying primary etiologic factors in 82% of the eyes and the bilateral occurrence in 5 patients. CONCLUSIONS: Meticulous SL examination aided by corneal imaging may accurately diagnose and determine the depth of corneal opacification as a cause for reduced vision. Histopathologically, the removed tissue is similar to PHSCD, but cases differ in their clinical profile. Peeling the thickened epithelial/subepithelial tissue is curative in most patients, improves visual and clinical outcome and avoids unnecessary corneal grafting.

Fundus albipunctatus and retinitis punctata albescens in a pedigree with an R150Q mutation in RLBP1.

Fundus albipunctatus (FA; OMIM 136880) is a rare form of apparently stationary night blindness characterized by the presence of myriad symmetrical round white dots in the fundus with a greater concentration in the midperiphery. A distantly similar but distinct clinical entity, retinitis punctata albescens (RPA), is also characterized by aggregation of irregular white flecks but is progressive and evolves to generalized atrophy of the retina. We studied 4 consanguineous kindreds diagnosed with FA from Saudi Arabia. Given the substantial phenotypic variation and overlap between different flecked retinal dystrophies, we evaluated all known genes associated with such conditions by both genetic analysis and direct sequencing. In one kindred, KKESH-099, we identified a homozygous R150Q alteration in RLBP1, the gene encoding the cellular retinaldehyde binding protein, associated previously with both recessive retinitis pigmentosa (arRP) and RPA. Examination of several patients aged 3-20 years over a 9-year period presented no evidence for either RP or RPA. In contrast, clinical examination of individuals with the same mutation in their fourth and fifth decade revealed signs consistent with RPA. The data suggest that the R150Q mutation in RLBP1 may result in RPA with slow progression. More importantly, younger individuals diagnosed with the milder disorder FA thought to be stationary may evolve to a more devastating and progressive phenotype.

Thermodynamic analysis of human retinal acetylcholinesterase inhibition using an anti-Alzheimer's drug, tacrine, through the development of a dual substrate and temperature model.

The present study determines the energy parameters, such as the Gibb's free energy change (deltaG), enthalpy change (deltaH), heat of activation (deltaH*), entropy change (deltaS), temperature coefficient (Q10) and activation energy (Ea), of human retinal acetylcholinesterase (AChE, EC 3.1.1.7) inhibition by tacrine. The stereo-frequency collisions factor (PZ, the number of sterically and energetically favorable collisions occurring between tacrine and AChE) was also studied in this investigation. Tacrine significantly increased the value of deltaG, deltaH, deltaH*, Q10, Ea and PZ factor, and decreased the value of deltaS for AChE. Since there is no known report on the inhibition of human retinal AChE by tacrine, these results were compared with the reported values for the energy parameters of camel retinal and chicken brain AChE inhibition by an anti-cancer drug, cyclophosphamide. The uniqueness of this approach lies in the development of the 'dual substrate and dual temperature' model, which may open up a new, more efficient avenue for the study of various enzyme catalyzed reactions.

Kinetic analysis of the toxicological effect of tacrine (Cognex) on human retinal acetylcholinesterase activity.

For the first time, kinetic parameters of the effect of tacrine, an anti-cholinesterase inhibitor of therapeutic potential in Alzheimer's disease has been studied on human retinal acetyl-cholinesterase (AChE). Tacrine inhibited the AChE activity in a concentration dependent manner, the IC(50) being about 45 nM. The Michaelis-Menten constant (K(m)) for the hydrolysis of acetylthiocholine iodide was found to be 0.120 mM and this value was increased by 4-52.8% in the presence of tacrine. V(max) was observed to be 2.23 micromol/h per mg protein for the control system, while it was decreased by 14.73-56.25% in the tacrine treated systems. Dixon as well as Lineweaver-Burk plots and their secondary replots indicated that the nature of the inhibition was of the mixed type, i. e. a combination of competitive and noncompetitive inhibition. The values of K(i) and K(I) were estimated to be as 37.76 and 64.36 nM, respectively.

Exclusion of AR-CHED from the chromosome 20 region containing the PPMD and AD-CHED loci.

Congenital hereditary endothelial dystrophy (CHED) is a disorder of the corneal endothelium and has been recognized to segregate in families with both autosomal dominant (AD) and autosomal recessive (AR) modes of transmission. AD-CHED has been previously linked to the pericentric region of chromosome 20. Posterior polymorphous dystrophy (PPMD), a corneal endothelial disorder showing phenotypic overlap with CHED, has also been previously genetically mapped to this region. The genetic interval containing AD-CHED is within the larger genetic interval containing the PPMD locus. This study sought to determine whether AR-CHED segregating in a consanguineous Saudi Arabian pedigree is linked to the previously mapped and overlapping loci for AD-CHED and PPMD on the pericentric region of chromosome 20. Forty members of a consanguineous Saudi Arabian pedigree segregating AR-CHED were ascertained. Short tandem-repeat polymorphic markers from the 20 cM interval on chromosome 20 containing both the PPMD and AD-CHED loci were used to genotype these individuals. LOD score analysis of the genotype data with the MENDEL software package utilizing a model of autosomal recessive inheritance with complete penetrance showed exclusion of CHED from the entire PPMD/AD-CHED interval by utilizing overlapping intervals of LOD scores of at least -2. The results obtained demonstrate that AR-CHED is not allelic to either AD-CHED or PPMD, although it has been proposed that AD-CHED may be allelic to PPMD. Thus, there are at least two genes responsible for CHED and PPMD.

Heparin surface-modified intraocular lenses in patients with inactive uveitis or diabetes.

OBJECTIVE: This study aimed to determine whether heparin surface-modified (HSM) intraocular lenses (IOLs) with a hydrophilic surface would reduce cell adherence and other postoperative changes compared with the conventional polymethylmethacrylate (PMMA) IOLs in patients with either diabetes mellitus or inactive uveitis. DESIGN: The study design was a randomized, double-masked, clinical trial. PARTICIPANTS: Twenty-five patients with bilateral cataracts, 14 with inactive anterior uveitis and 11 with diabetes, with an age range of 11 to 81 years (mean, 52.8 years) participated. INTERVENTION: Bilateral cataract extraction with posterior chamber IOL implantation was measured, each patient receiving an HSM lens in one eye and a PMMA lens in the other. Pharmacia one-piece HSM and PMMA IOLs were used. Postoperative ocular changes were evaluated at regular intervals for 24 months in patients with inactive uveitis and for 6 months in patients with diabetes. Patients and physicians alike were unaware of which eye contained which lens until postoperative results were compiled. Records were kept by a study coordinator. MAIN OUTCOME MEASURES: Comparisons of posterior synechiae, IOL cellular deposits, and posterior capsular fibrosis between PMMA and HSM IOLs were measured. RESULTS: Using the chi-square test, no statistically significant difference was found between the HSM and PMMA IOLs in the number of cellular deposits found on the anterior IOL surface, the number of adhesions between the iris and IOL, or the incidence of capsular opacification. CONCLUSION: The HSM and PMMA IOLs showed similar postoperative results in patients with inactive uveitis or diabetes mellitus.

An immunohistochemical study of collagens in trachoma and vernal keratoconjunctivitis.

PURPOSE: To analyse the distribution and types of collagen in the conjunctiva of patients with trachoma and vernal keratoconjunctivitis (VKC). METHODS: Conjunctival biopsy specimens were collected from 9 patients with active trachoma, 9 patients with scarred trachoma, 6 patients with active VKC and 9 control subjects. The presence and distribution of collagen was assessed microscopically with immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies directed against types I, III, IV and V collagen. RESULTS: In normal conjunctiva, the staining for types I and III collagen was localised to the substantia propria. Type IV collagen was located in the epithelial, vascular endothelial and accessory lacrimal gland basement membranes. Staining for type V collagen was absent. New type V collagen deposition close to basement membranes was noted in active trachoma, scarred trachoma and VKC. The extent of deposition of type V collagen was markedly increased in scarred trachoma when compared with active trachoma. Staining for type IV collagen showed irregularly thickened epithelial basement membrane in active trachoma, and a marked increase in basement membrane type IV collagen was noted in scarred trachoma. Immunoreactivity of types I and III collagen increased in active trachoma and decreased in scarred trachoma. VKC conjunctiva contained increased amounts of types I, III and IV collagen due to marked increase in the thickness of vascular endothelial basement membrane and very prominent deposition of types I and III collagen around stromal vessels. CONCLUSIONS: Our data indicate new type V collagen formation in the conjunctiva from patients with active trachoma, scarred trachoma and VKC. Increased deposition of types I, III and IV collagen is noted in VKC and active trachoma. Our findings suggest that increased deposition of type IV collagen and new type V collagen formation contributes to the development of conjunctival fibrosis in scarred trachoma.

Penetrating keratoplasty in congenital hereditary endothelial dystrophy.

PURPOSE: The purpose of the study is to determine the outcome of penetrating keratoplasty in congenital hereditary endothelial dystrophy. METHODS: Records of 40 patients (13 males, 27 females) who underwent penetrating keratoplasty (56 eyes) were reviewed. The mean age at surgery was 11.8 years (range, 2 months-35 years). The mean follow-up was 37 months (range, 6-136 months). RESULTS: In 35 (62.5%) of 56 eyes that underwent primary penetrating keratoplasty, the grafts survived. Graft survival analysis showed the probability of obtaining a clear graft is 92% at 1 year, 72% at 2 years, and 56.5% at 5 years. Graft survival was statistically better in eyes where onset of the disease is delayed (P = 0.02), if the graft donor age is between 5 and 30 years versus older than 30 years (P = 0.02), and for patients who kept follow-up appointments versus those who were delinquent (P < 0.03). Visual acuity was 20/40 in 1.9%, 20/50 to 20/80 in 18.9%, 20/100 to 20/300 in 49%, and less than 20/400 in 30.2%. The main causes of graft failure were graft rejection (six eyes) and bacterial keratitis (four eyes). CONCLUSIONS: Penetrating keratoplasty in congenital hereditary endothelial dystrophy is moderately successful, and graft survival is better in cases of delayed onset compared with that of congenital onset. Early surgical intervention is recommended to prevent development or progression of amblyopia.

Phacoemulsification at King Khaled Eye Specialist Hospital--the experience of the past.

OBJECTIVE: To study the outcome of phacoemulsification (PE) compared to standard extracapsular surgery before the introduction of state-of-the-art techniques (capsulorhexis, hydrodissection, nuclear cracking, nuclear chopping, sutureless incisions) and sophisticated equipment. STUDY DESIGN: Charts from 375 patients (453 eyes) undergoing PE between 1984 and 1989 were randomly selected and studied retrospectively. A minimum age of 35 years, and a minimum follow-up of three months were required. SETTING: A large eye hospital in the Kingdom of Saudi Arabia staffed with an international faculty of ophthalmic surgeons. PATIENTS: Patients over 35 years of age undergoing PE for immature, mature and traumatic cataract. MAIN OUTCOME MEASURES: Postoperative visual acuity, and rate or frequency of intraoperative complications. RESULTS: 66.5% achieved visual acuity of 20/40 or better, which compares favourably with the 36.5% of eyes reaching this level of visual acuity after mainly standard extracapsular cataract surgery in another study at our hospital. Posterior capsule ruptures occurred in 7.5% and vitreous loss in 5.5%. Other ocular disease (odds ratio 7.51 confidence interval 4.43-12.7) and intraoperative complications (odds ratio 2.97 confidence interval 1.38-6.42) were statistically significant predictors for final visual acuity of under 20/40 (p = < 0.001 and 0.005 respectively). CONCLUSION: The outcome of PE was better than that of standard extracapsular cataract extraction in the same setting. However, since PE appeared to be used selectively, no clear advantage compared to extracapsular cataract extraction is evident in the period before the introduction of modern state-of-the-art PE-techniques.

Recurrence of climatic droplet keratopathy. Two case reports.

Climatic droplet keratopathy (CDK) is characterized by a band-shaped pattern of subepithelial opacities and golden-yellow spherules. Recurrence of this disease in corneal grafts has not been reported. We report two cases that developed recurrence of this disease in corneal grafts done for CDK, 3 1/2 years following lamellar penetrating keratoplasty and 6 years following penetrating keratoplasty. This illustrates the possibility of this degenerative disease to recur in a few years if aetiological factors are persistently present.

Photorefractive keratectomy after radial keratotomy.

BACKGROUND: Twenty-three eyes of 22 patients remained undercorrected 5 to 49 months after radial keratotomy, either alone or in combination with transverse keratotomy. METHOD: We attempted to correct the residual myopia ranging from -1.25 to -5.75 diopters (D) (with astigmatism of 0 to 1.25 D) with photorefractive keratectomy. The mean age of patients was 26 years (range 22 to 40 years). RESULTS: After photorefractive keratectomy (follow-up 6 to 17 months) uncorrected visual acuity was equal to or better than 20/20 in 39% (9 eyes), better than 20/25 in 65% (15 eyes), and better than 20/40 in 74% (17 eyes). Spectacle-corrected visual acuity was equal or better than 20/40 in all eyes; one eye (4%) lost two lines of spectacle-corrected visual acuity. Refractive error was within +/- 0.50 D in 48% (11 eyes) and within +/- 1.00 D in 65% (15 eyes). Undercorrections of more than 1.00 D occurred in 22% (5 eyes) and overcorrections of more than 1.00 D occurred in 13% (3 eyes). No or minimal haze was present in 57% (13 eyes), mild haze in 39% (9 eyes) and moderate haze in 4% (1 eye). Final uncorrected visual acuity was better (p = 0.0002) and haze was less (p = 0.003) in the group with less than -3.00 D than in the group with greater than or equal to -3.00 D. CONCLUSION: Photorefractive keratectomy after radial keratotomy is safe but less effective and less predictable in eyes with greater than or equal to -3.00 D compared to those with less than -3.00 D.

Epithelial inclusion cysts following epikeratoplasty.

BACKGROUND: Epikeratoplasty for keratoglobus performed to tectonically support the thin globular cornea may have complications such as interface opacities. METHODS: We report the case of a patient with persistent interface opacities and epithelial cysts following epikeratoplasty for keratoglobus that were treated primarily by washouts and repeated argon laser photocoagulation. RESULTS: Interface opacities led to massive epithelial inclusion cysts. Direct removal of these cysts and placement of a new lamellar graft resulted in a favorable outcome. CONCLUSION: Massive epithelial inclusion cysts may develop in the lamellar interface after epikeratoplasty. Direct surgical removal was successful.

Bacterial keratitis following phototherapeutic keratectomy.

BACKGROUND: Phototherapeutic keratectomy (PTK) is effective in the treatment of many superficial corneal disorders. The incidence of bacterial keratitis following PTK has not been assessed in a large, prospective clinical trial. METHODS: We report three cases of bacterial keratitis that occurred in a prospective study of 258 consecutive PTK procedures at King Khaled Eye Specialist Hospital. RESULTS: Three (1.2%) of 258 eyes developed bacterial keratitis during a period of follow up ranging from 1 to 24 months. All three cases were in 183 eyes (1.6%) with a diagnosis of climatic droplet keratopathy, while no cases were observed in 75 eyes with other anterior corneal disorders. Gram-positive species (Streptococcus pneumonia in two, coagulase-negative Staphylococcus in one) were the predominant species isolated from all three cases. Two of the cases were polybacterial. The final visual outcomes ranged from 20/125 to 20/400. CONCLUSIONS: The risk of bacterial keratitis following treatment of superficial corneal disorders with PTK is low but its occurrence may adversely affect the final visual outcome.

The histopathology and the mechanism of entropion in patients with trachoma.

BACKGROUND: Eyelids of patients with trachoma may be thickened. This thickening could be attributed to trachomatous changes in the conjunctiva and tarsus. METHODS: Biopsies of tarsal plates and palpebral conjunctivae were obtained from 17 upper eyelids of 11 patients with inactive trachoma who underwent posterior tarsotomy procedures for entropion repair. RESULTS: Light microscopy studies showed a thick and compact subepithelial fibrous membrane adherent to the tarsal plate. This membrane caused apparent thickening of the tarsus when measured intraoperatively (range, 1.25-2.00 mm). Other histopathologic findings include atrophy of the meibomian glands with thickening of the acinar basement membrane, loss of goblet cells, retention cysts, and hyaline degeneration of the tarsal plate with focal replacement by adipose tissue. CONCLUSION: The contraction of the subepithelial fibrous membrane formed by vertically oriented parallel collagen fibers is one of the main factors contributing to the entropion formation.

Prevalence and causes of visual impairment and blindness in the south western region of Saudi Arabia.

A population-based survey of the prevalence of major causes of blindness and visual impairment was conducted in Bisha region, Saudi Arabia. Overall, 2882 people were examined. The prevalence of blindness (visual acuity of < 3/60 in the better eye with best available correction) was 0.7% and the prevalence of visual impairment (visual acuity < 6/12 but > or = 3/60 in the better eye with best available correction) was 10.9%. Cataracts were responsible for 52.6% of blindness and 20.6% of visual impairment. Refractive errors accounted for 67.9% of visual impairment. Proper management of cataracts and correction of refractive errors will cure 73.6% of blind subjects and 88.5% of visually handicap people in this part of the world.

Neodymium:YAG laser iridotomy in the initial management of phacomorphic glaucoma.

Acute angle-closure glaucoma can be triggered by a mature or intumescent cataract, and occurs in eyes with open angles, as well as in those with narrow, occludable angles. This is encountered more in developing countries, where patients present late. They tend to wait until the cataract becomes mature, because it is common belief among these patients that cataracts should not be operated on until vision drops to the level of hand movements or light perception. The authors reviewed the charts of 10 patients who were treated for phacomorphic glaucoma, by first undergoing neodymium:YAG (Nd:YAG) laser iridotomy. In all patients, the acute angle-closure glaucoma attack could be reversed or prevented by the iridotomy, before subsequent cataract extraction. The value of Nd:YAG laser iridotomy in the initial management of phacomorphic glaucoma is discussed.

Climatic droplet keratopathy with corneal amyloidosis.

Climatic droplet keratopathy (CDK) is a degenerative disease of the cornea, highly prevalent in Saudi Arabia. It is characterized by aggregates of small, golden-yellow globules that accumulate in the subepithelial layers, Bowman's layer, and the superficial stroma of the cornea. The authors report on 22 patients (40 eyes) with CDK and lattice lines in the cornea. The condition occurred late in life (mean age, 67 years). It was bilateral in 82% of patients, with no family history of lattice dystrophy or systemic amyloidosis. These lines were found in all layers of the stroma. Results of histopathologic and electron microscopic examination of the lattice lines confirmed the presence of amyloid. Results of immunohistochemical examination showed evidence of deposition of AP protein. The cause of these deposits in the cornea is not known, but the authors speculate that environmental factors causing CDK also may play a role in the deposition of protein AP in the cornea. The contribution of trachoma to the degenerative changes in the cornea and secondary amyloidosis could not be ruled out, as all patients had inactive trachoma. Climatic droplet keratopathy with corneal amyloidosis, therefore, represents a form of "lattice degeneration" of the cornea.