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Biomedical subjects

Khalid F Tabbara

Publications and source records attributed to Khalid F Tabbara.

17 recordsLinked to original sources
PubMed2006

Aspergillus fumigatus colonization of punctal plugs.

PURPOSE: Punctal plugs are used in patients with dry eye syndrome to preserve the tears. In this report, I present two cases of Aspergillus fumigatus colonization of punctal plugs. DESIGN: Observational series of two cases. METHODS: Approval was obtained from the institutional review board. Two men aged 29 and 31 years developed black spots inside the hole of punctal plug, which looked like eyeliner deposits. The deposits inside the hole of the plug in each patient were removed and cultured. RESULTS: Cultures of the two punctal plugs black deposits grew A fumigatus. Bacterial cultures were negative. CONCLUSIONS: Colonization of the punctal plug hole with A fumigatus was observed in two cases. It is recommended that punctal plugs be removed in patients undergoing refractive or intraocular procedures or in patients who are receiving topical corticosteroids. Current punctal plugs should be redesigned to avoid the presence of an inserter hole.

Adult↗
PubMed2006

Evaluation of the effect on outcomes of the route of administration of corticosteroids in acute Vogt-Koyanagi-Harada disease.

PURPOSE: To compare the effect on outcomes of the route of administration of corticosteroids in acute Vogt-Koyanagi-Harada disease. DESIGN: Retrospective comparative interventional case series. METHODS SETTINGS: Nine international uveitis specialty clinics. STUDY POPULATION: Forty-eight patients presenting over a three-year period to a study center with acute Vogt-Koyanagi-Harada disease. INTERVENTION: Initial treatment with corticosteroid either orally (Oral only group) or intravenously followed by an oral taper (IV+Oral group). MAIN OUTCOME MEASURES: Change in visual acuity with treatment; development of ocular complications, including visually significant cataract, choroidal neovascularization, subretinal fibrosis, fundus pigment migration, nummular hypopigmented lesions, and diffuse fundus depigmentation; use of immunosuppressive therapy. RESULTS: The Oral only group comprised 15 patients (31%) and the IV+Oral group 33 patients (69%). Median follow-up was 15 months. There was no difference in duration of follow-up between groups (P = .234). There was no difference in the change in visual acuity between groups, adjusting for initial visual acuity (P = .402). There were no differences in the rates of development of visually significant cataract, fundus pigmentary changes, or in the rate of use of subsequent immunosuppressive therapy between treatment groups. No patients developed choroidal neovascularization or subretinal fibrosis over the study period. CONCLUSIONS: Route of administration of corticosteroid had no detectable effect on change in visual acuity nor on the development of visually significant complications over the study period. Prospective trials are necessary to address speed of resolution and definitively answer outcome questions.

Acute Disease↗
PubMed2006

Risk factors for corneal ectasia after LASIK.

PURPOSE: To establish a grading system that helps identify high-risk individuals who may experience corneal ectasia after LASIK. DESIGN: Retrospective, comparative, interventional case series. PARTICIPANTS: One hundred forty-eight consecutive patients (148 eyes) were included in this study. Thirty-seven patients who underwent LASIK at other refractive centers experienced corneal ectasia in 1 eye after LASIK. One hundred eleven eyes of 111 patients who underwent successful LASIK during the same period were age and gender matched and served as controls. INTERVENTION: All patients underwent preoperative and postoperative topographic analysis of the cornea. The follow-up period in both groups of patients ranged from 2 to 5 years, with a mean follow-up of 3.6 years. All patients underwent LASIK for myopia (spherical equivalent, -4.00 to -8.00 diopters). MAIN OUTCOME MEASURES: Corneal keratometry, oblique cylinder, pachymetry, posterior surface elevation, difference between the inferior and superior corneal diopteric power, and posterior best sphere fit (BSF) over anterior BSF were given a grade of 1 to 3 each. An ectasia grading system was established, and the cumulative risk score was assessed. RESULTS: Patients who had a grade of 7 or less showed no evidence of corneal ectasia, whereas 16 (59%) of 27 patients who had a grade of 8 to 12 had corneal ectasia. Twenty-one (100%) of 21 patients with a grade of more than 12 had corneal ectasia after LASIK (P<0.0001). CONCLUSIONS: A risk score may help in the prediction of patients who are at risk of experiencing corneal ectasia after LASIK. A prospective clinical study is needed to assess the validity of these risk factors.

Cornea↗
PubMed2006

Childhood blindness at a school for the blind in Riyadh, Saudi Arabia.

PURPOSE: To determine the major causes of eye diseases leading to visual loss and blindness among children attending a school for the blind in Riyadh, Saudi Arabia. METHODS: A total of 217 school children with visual disabilities attending a school for the blind in Riyadh were included. All children were brought to The Eye Center, Riyadh, and had complete ophthalmologic examinations including visual acuity testing, biomicroscopy, ophthalmoscopy, tonometry and laboratory investigations. In addition, some patients were subjected to electroretinography (ERG), electrooculography (EOG), measurement of visual evoked potentials (VEP), and laboratory work-up for congenital disorders. RESULTS: There were 117 male students with an age range of 6-19 years and a mean age of 16 years. In addition, there were 100 females with an age range of 6-18 years and a mean age of 12 years. Of the 217 children, 194 (89%) were blind from genetically determined diseases or congenital disorders and 23 (11%) were blind from acquired diseases. The major causes of bilateral blindness in children were retinal degeneration, congenital glaucoma, and optic atrophy. The most common acquired causes of childhood blindness were infections and trauma. CONCLUSION: The etiological pattern of childhood blindness in Saudi Arabia has changed from microbial keratitis to genetically determined diseases of the retina and optic nerve. Currently, the most common causes of childhood blindness are genetically determined causes. Consanguineous marriages may account for the autosomal recessive disorders. Public education programs should include information for the prevention of trauma and genetic counseling. Eye examinations for preschool and school children are mandatory for the prevention and cure of blinding disorders.

Adolescent↗
PubMed2005

Effects of dehydration on corneal tissue absorption of topical azithromycin in rabbits.

PURPOSE: To assess the corneal tissue absorption of azithromycin in desiccated and normal eyes of rabbits. METHODS: A total of 25 New Zealand Albino rabbits weighing 2-3 kg each were included. One eye of each rabbit was desiccated. The other eye was left as control. Azithromycin 1.5% topical eyedrops were instilled in both eyes. Five rabbits were sacrificed at each of the following time points: 30 min, 3 hr, 6 hr, and 12 hr. Corneal tissues specimens were subjected to high-performance liquid chromatography mass spectrometry. A paired t test was used to evaluate the statistical difference in corneal tissue absorptions of azithromycin at each time point. RESULTS: The mean corneal tissue levels of azithromycin in dry eyes were 66.3 microg/ml, 92.6 microg/ml, 117.5 microg/ml, and 179.9 microg/ml, and the mean corneal tissue levels of azithromycin in normal eyes were 42.0 microg/ml, 43.4 microg/ml, 43.3 microg/ml, and 80.0 microg/ml at 30 min, 3 hr, 6 hr, and 12 hr respectively. Both groups showed increase in corneal tissue absorption overtime (p < 0.0001). Significantly higher levels of azithromycin were noted in dry eyes at each time point except at the 30-min time point. CONCLUSIONS: This study demonstrated that corneas exposed to desiccation showed statistically significant increase in azithromycin level compared to normal eyes.

Absorption↗
PubMed2005

Retinal vasculitis.

Retinal vasculitis is a sight-threatening intraocular inflammation affecting the retinal vessels. It may occur as an isolated ocular condition, as a manifestation of infectious or neoplastic disorders, or in association with a systemic inflammatory disease. The search for an underlying etiology should be approached in a multidisciplinary fashion based on a thorough history, review of systems, physical examination, and laboratory evaluation. Discrimination between infectious and noninfectious etiologies of retinal vasculitis is important because their treatment is different. This review is based on recently published articles on retinal vasculitis and deals with its clinical diagnosis, its link with systemic diseases, and its laboratory investigation.

Diagnosis, Differential↗
PubMed2005

Azithromycin prophylaxis and treatment of murine toxoplasmosis.

OBJECTIVE: To evaluate the azithromycin effects alone and in combination with other agents in the prophylaxis and treatment of murine toxoplasmosis. METHODS: A total of 280 BALB/c mice were included, and 2 x 103 Toxoplasma organisms of the RH strain Toxoplasma gondii strain ATCC50174 were given intraperitoneally to each mouse. In experiment one, 40 animals were given azithromycin 200 milligram/kilogram/daily for 3 days starting the day of inoculation, 40 mice were control. In experiment 2, the treatment was started 48 hours after inoculation and given daily for 3 days: one group received azithromycin 200 milligram/kilogram/day, the second group received pyrimethamine 25 milligram/kilogram/day, and the sulfadiazine 100 milligram/kilogram/day. The third group was control. In experiment 3, 7 groups of animals received one of the following (1) none, (2) azithromycin 200 milligram/kilogram/day, (3) pyrimethamine 25 milligram/kilogram/day and sulfadiazine 100 milligram/kilogram/day, (4) azithromycin and sulfadiazine, (5) azithromycin and pyrimethamine, (6) azithromycin with sulfadiazine and pyrimethamine, (7) sulfadiazine alone. Treatment was initiated 72 hours after inoculation for 3 days. The study was conducted at the Animal Care Facility of King Saud University, Riyadh, Kingdom of Saudi Arabia. RESULTS: Animals that received azithromycin simultaneously with inoculation survived, and all control animals died. All animals died in groups receiving single drug therapy. Animals treated with azithromycin and sulfadiazine showed a survival rate of 40%, sulfadiazine and pyrimethamine 40%, or azithromycin with sulfadiazine and pyrimethamine 95% (p<0.0001). CONCLUSION: Azithromycin alone was found to be effective in the prophylaxis of murine toxoplasmosis. Combination therapy was effective in the treatment of murine toxoplasmosis.

Animals↗
PubMed2004

Prevention of ligneous conjunctivitis by topical and subconjunctival fresh frozen plasma.

PURPOSE: To present a case of ligneous conjunctivitis where the recurrence of membranous conjunctivitis was prevented by subconjunctival and topical instillation of fresh frozen plasma. DESIGN: Interventional case report. METHODS: A case of ligneous conjunctivitis with multiple recurrences since the age of 3 years developed recurrent membranous conjunctivitis after transconjunctival levator recession. Blood plasminogen activity was determined. The membrane was excised, and the membrane reappeared 4 days later. The patient was treated with excision of the membrane and subconjunctival injection of fresh frozen plasma and topical fresh frozen plasma. Plasminogen activity of the fresh frozen plasma was normal. RESULTS: Plasminogen blood functional activity was 52% (normal is 80%-120%). The patient had complete remission with no recurrences of membranous conjunctivitis after topical and subconjunctival fresh frozen plasma. CONCLUSIONS: Prophylactic use of topical and subconjunctival fresh frozen plasma may help in the prevention of membranes in susceptible patients with plasminogen deficiency.

Administration, Topical↗
PubMed2004

New formula for calculating intraocular lens power after laser in situ keratomileusis.

PURPOSE: To assess the validity and accuracy of a proposed formula for keratometry (K) readings after laser in situ keratomileusis (LASIK). SETTING: The Eye Center and the Eye Foundation for Research, Riyadh, Saudi Arabia. METHOD: This studied comprised 34 eyes that had LASIK surgery. Refraction and an automated K-reading (auto-K) were performed preoperatively. Refraction, auto-K, and K-reading assessment by the clinical history method and the proposed formula were performed 4 to 12 weeks postoperatively. The proposed formula is K(postop) = K(preop) - [(N(c) - 1) x (R(a-postop) - R(a-preop))/(R(a-postop) x R(a-preop))], where K(postop) is the K-reading after LASIK, K(preop) is the K-reading before LASIK, N(c) is the index of refraction of the cornea (1.376), R(a-postop) is the radius of curvature of the anterior corneal surface after LASIK, and R(a-preop) is the radius of curvature of the anterior corneal surface before LASIK. RESULTS: Twenty patients (10 men, 10 women) were included in the study. The mean age of the patients was 30.58 years +/- 17.68 (SD) (range 18 to 44 years). Preoperatively, the mean spherical equivalent (SE) was -4.99 +/- 2.82 diopters (D) (range -1.12 to -15.00 D), the mean R(a) was 7.76 +/- 0.32 mm (range 7.33 to 8.50 mm), and the mean auto-K reading was 43.45 +/- 1.73 D (range 39.62 to 46.00 D). Postoperatively, the mean SE was +0.02 +/- 0.63 D (range -2.75 to +1.00 D), the mean R(a) was 8.63 +/- 0.53 mm (range 7.80 to 9.92 mm), and the mean K-reading assessed by auto-K, clinical history method, and the proposed formula was 39.17 +/- 2.35 D (range 34.00 to 43.25 D), 38.79 +/- 2.52 D (range 33.1 to 42.78 D), and 38.69 +/- 2.51 D (range 33.1 to 43.0 D), respectively. The results obtained by the proposed formula were similar to those obtained by the clinical history method (P =.098). Auto-K readings significantly overestimated the K-values (P<.0001) when compared to the proposed formula and clinical history method. CONCLUSION: The proposed formula was simple, objective, not dependent on refraction, and as accurate as the clinical history method in determining K-readings after LASIK.

Adolescent↗
PubMed2002

Causes of uveitis at The Eye Center in Saudi Arabia: a retrospective review.

AIMS AND BACKGROUND: The main objective of this study was to determine the causes of uveitis at a referral center in Riyadh, Saudi Arabia. METHODS: We carried out a retrospective review of clinical records of 200 uveitis cases referred to The Eye Center, a referral center in Riyadh, Saudi Arabia. There were 120 (60%) males and 80 (40%) females with an age range of 7 to 91 years and a mean age of 35 (SD +/- 17). Patients had complete ophthalmic and medical examinations. Laboratory studies were requested whenever indicated. Patients were followed up for a minimum of 12 months. RESULTS: In the period 1995-2000, we encountered 200 cases of uveitis among a total of 20,191 consecutive new cases, yielding a prevalence of 1%. Acute anterior uveitis of undetermined origin was found in 58 (29%) of 200 patients. There were 13 (6.5%) cases of Behçet's disease, 7 (3.5%) of Fuchs' heterochromic iridocyclitis, 6 (3%) of sarcoidosis, and 5 (2.5%) patients had Vogt-Koyanagi-Harada syndrome (VKH). Among the infectious causes, herpetic uveitis was found in 32 (16%) patients, tuberculosis in 21 (10.5%), and toxoplasmosis in 13 (6.5%) cases. Seventeen (8.5%) cases were of miscellaneous origin and in 28 (14%) cases the etiologic diagnosis was undetermined. CONCLUSION: Acute anterior uveitis of undetermined origin was the most common cause of uveitis, followed by Behçet's disease. Herpetic uveitis was the most common infectious cause of uveitis. Ocular tuberculosis and toxoplasmosis were found to be common causes of infectious uveitis at this referral center in Saudi Arabia.

Adolescent↗
PubMedDate not supplied

Presumed reactivation of herpes zoster ophthalmicus following laser in situ keratomileusis.

PURPOSE: To report a case of herpes zoster ophthalmicus reactivation following laser in situ keratomileusis (LASIK) for myopia. METHODS: A 54-year-old healthy male underwent uneventful bilateral LASIK for the correction of myopia and astigmatism (-5.75 -3.00 x 20 degrees right eye, -5.50 -3.00 x 170 degrees left eye). Two months following LASIK, an epithelial dendritic lesion appeared in the lower third of the corneal flap of the left eye with vesiculoulcerative lesions of the lateral side of the tip of the nose. RESULTS: The patient was treated with topical and oral antiviral agents and had complete recovery of the lesions in 10 days. CONCLUSIONS: Herpes zoster reactivation may occur following LASIK. Reactivation of herpes zoster in this case could have been coincidental, or secondary to LASIK and the subsequent use of topical corticosteroids following LASIK.

Astigmatism↗
PubMedDate not supplied

Intraocular lens power calculation following LASIK: determination of the new effective index of refraction.

PURPOSE: To determine the new corneal effective index of refraction (rN) following LASIK to be used for accurate keratometry reading (K-reading). METHODS: A total of 332 eyes that underwent myopic LASIK were divided into two groups (group A [n = 137] and group B [n = 1951). In each group, patients were divided into four subgroups according to the amount of spherical equivalent refraction of myopic LASIK ablation (subgroup 1 [< -4.0 D], subgroup 2 [-4.0 to < -8.0 D], subgroup 3 [-8.0 to -12.0 D], and subgroup 4 [> -12.0 D]). In each subgroup of group A, K-reading was measured by the clinical history method and the new corneal effective index (rN) was determined using paraxial formula: (K-reading = (rN-1)/Ra), where Ra is the radius of curvature of the anterior corneal surface. In group B, the anterior radius of curvature of the cornea was determined by automated K-reading, and K-reading was measured in each subgroup using the new effective index in paraxial formula, clinical history method, and automated K-reading. RESULTS: In group A, the new effective index of refraction was 1.3355, 1.3286, 1.3237, and 1.3172 in the four subgroups, respectively. In group B, the mean K-reading measurements using rN in paraxial formula, clinical history method, and automated K-reading were: 40.33 +/- 1.68 D, 40.33 +/- 1.67 D, and 40.54 +/- 1.69 D, respectively, in subgroup 1; 37.96 +/- 1.26 D, 38.03 +/- 1.38 D, and 38.98 +/- 1.28 D, respectively, in subgroup 2; 35.77 +/- 1.75 D, 35.84 +/- 1.85 D, and 37.29 +/- 1.83 D, respectively, in subgroup 3; and 34.03 +/- 1.49 D, 34.15 +/- 1.84 D, and 36.21 +/- 1.59 D, respectively, in subgroup 4. In all subgroups of group B, the results of K-reading obtained using the new effective index of refraction were statistically similar to the results obtained by clinical history method (P > .05). Automated K-reading statistically overestimated the K-reading values in subgroups 2, 3, and 4 of group B (P < .001). CONCLUSIONS: The use of the new corneal effective index of refraction allows for an accurate derivation of K-reading from the anterior radius of curvature.

Cornea↗
PubMedDate not supplied

Pattern of childhood blindness at a referral center in Saudi Arabia.

BACKGROUND: An understanding of the causes of blindness and the magnitude of the problem is crucial in designing effective intervention and prevention programs. We undertook this retrospective review to determine the causes of childhood blindness at an eye referral center. PATIENTS AND METHODS: We reviewed charts of children who presented between August 1997 and August 2003. All children had a complete ophthalmologic examination. Blindness was defined as a visual acuity < 20/400, visual impairment as visual acuity between 20/400 and 20/60, and visual loss as a visual acuity < 20/60. RESULTS: A total of 5217 children included 220 (59%) males and 152 (41%) females (age range 2 to 18 years, mean age, 10 years). One hundred twelve (2%) were blind and 260 (5%) had visual impairment. The most common causes of bilateral blindness included optic nerve diseases, retinal disorders, and cataract. The most common causes of unilateral blindness included trauma, retinal diseases, refractive errors, and optic nerve diseases. The most common causes of bilateral visual impairment included refractive errors, corneal diseases, retinal disorders, cataract, and congenital nystagmus. Genetically determined disorders were observed in 37 (70%) of 53 patients with bilateral blindness, and in 52 (56%) of 93 patients with bilateral visual impairment. The incidence of consanguinity among parents of children with acquired causes was 2 (3%) of 59 patients compared to 34 (38%) of 89 among genetically determined causes (P < 0.001). CONCLUSION: Genetically determined disorders continue to play an important role in the causation of childhood blindness among patients attending our referral center in Saudi Arabia. Genetic counseling, early eye screening of children and public education may help in the prevention of visual disorders in children.

Adolescent↗