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PubMed2004

Refractive adaptation in amblyopia: quantification of effect and implications for practice.

AIM: To describe the visual response to spectacle correction ("refractive adaptation") for children with unilateral amblyopia as a function of age, type of amblyopia, and category of refractive error. METHOD: Measurement of corrected amblyopic and fellow eye logMAR visual acuity in newly diagnosed children. Measurements repeated at 6 weekly intervals for a total 18 weeks. RESULTS: Data were collected from 65 children of mean (SD) age 5.1 (1.4) years with previously untreated amblyopia and significant refractive error. Amblyopia was associated with anisometropia in 18 (5.5 (1.4) years), strabismus in 16 (4.2 (0.98) years), and mixed in 31 (5.2 (1.5) years) of the study participants. Mean (SD) corrected visual acuity of amblyopic eyes improved significantly (p<0.001) from 0.67 (0.38) to 0.43 (0.37) logMAR: a mean improvement of 0.24 (0.18), range 0.0-0.6 log units. Change in logMAR visual acuity did not significantly differ as a function of amblyopia type (p = 0.29) (anisometropia 0.22 (0.13); mixed 0.18 (0.14); strabismic 0.30 (0.24)) or for age (p = 0.38) ("under 4 years" 0.23 (0.18); "4-6 years" 0.24 (0.20); "over 6 years" 0.16 (0.23)). CONCLUSION: Refractive adaptation is a distinct component of amblyopia treatment. To appropriately evaluate mainstream therapies such as occlusion and penalisation, the beneficial effects of refractive adaptation need to be fully differentiated. A consequence for clinical practice is that children may start occlusion with improved visual acuity, possibly enhancing compliance, and in some cases unnecessary patching will be avoided.

Adaptation, Ocular↗
PubMed1992

Assessment of visual function in autistic children.

Children with autism demonstrate "atypical" gaze or social "looking" and frequently manifest such sterotypies as eye pressing, hand flicking, and light gazing. This study's purpose was to evaluate autistic children for visual dysfunction that may be related to the manifested visual signs and symptoms. Thirty-four autistic children, ages 2 to 11 years (median age = 7 years, 6 months) were evaluated for ocular alignment, refractive error, visual acuity, oculomotility skills, and stereopsis. None of the children manifested ocular disease, known seizure disorders, or dysmorphic features. Their developmental levels ranged from average intelligence to severely retarded. Binocular visual acuity was measured with the acuity card procedure. Monocular visual acuity was not obtained. Refractive errors ranged from -4.25 to +3.25 D; the median was plano with the near retinoscopy technique. Of the 34 children, 21% were strabismic at far and 18% were strabismic at near. Lang stereo testing was attempted on all children and completed on 17. Of the 17, all but 3 exhibited 550 sec arc. Only 14.7% of the children exhibited voluntary pursuit movements, and all the children demonstrated saccadic fixations. Thirty-one children had atypical optokinetic nystagmus (OKN) responses such as delayed onset, short duration, gaze avoidance, or stereotypic behavior. Repeated testing revealed consistent visual responses on OKN and visual acuity. Given these findings, research with this population should be pursued further.

Autistic Disorder↗
PubMed2005

[Frequency and incidence of myopia among medical students].

PURPOSE: To estimate the frequency and dynamic changes in refractive errors in population of students of medical (MF) and dental (DF) faculties of Pommeranian Medical Academy in Szczecin. MATERIAL AND METHODS: Medical records from ophthalmic examinations performed in 176 medical students (117 females and 59 males) during the 2nd and 4th course of studies were analyzed (2-years long observation). RESULTS: Refractive error was found in 42% of MF students and 39.5% of DF students on the 2nd course and in 51% and 47% on the 4th course respectively. Myopia was found in 75% of ametropic eyes. In 2 years observation time, there was a statistically significant progression of refracive error in 50% of myopic students (from -2.9 +/- 2.3 D to -3.4 +/- 1.9D in MF and from -2.0 +/- 1.5 to -2.4 +/- 1.5D in DF). Myopia developed in 13% of initially emmetropic students.

Adult↗
PubMed1980

The vision of submariners and National Guardsmen: A longitudinal study.

This study was designed to differentiate among possible causes of an increased incidence of myopia and related symptoms among submariners by making a longitudinal comparison of the visual functions of two groups of subjects, submariners and National Guardsmen. Refractive error, visual acuity, phorias, accommodation, and depth perception were measured. Submariners showed statistically significantly greater losses in visual acuity, accommodation, and depth perception over a 3.5-year period than did the guardsmen, but the differences were very small. Comparison with data in the literature gives evidence of large shifts in refractive error for young men, both submariners and guardsmen, born in recent years. it is suggested that whatever factors are responsible for the increase in myopia in the general population are operating even more effectively among submariners.

Accommodation, Ocular↗
PubMed2006

Modified intracorneal ring segment implantations (INTACS) for the management of moderate to advanced keratoconus: efficacy and complications.

PURPOSE: To evaluate the safety and efficacy of modified intracorneal ring segment implantation (INTACS) in the management of moderate and advanced keratoconus (KCN). METHODS: A modified procedure of intracorneal ring segment (INTACS) implantation was performed in eyes with moderate to advanced keratoconus that were intolerant to contact lens or spectacle correction. The main outcome measures were uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), refraction, and keratometry. The preoperative values were compared with the values 6 and 12 months postoperatively. RESULTS: Implantation was performed on 20 eyes of 15 patients; 9 were female and 6 were male. The mean age was 30.2 years (SD +/- 5.44; range, 23-40). At the 6-month follow-up, UCVA improved from 20/154 (SD +/- 0.11) preoperatively to 20/28 (SD +/- 0.21) postoperatively (P < 0.05); BCSVA improved from 20/37 (SD +/- 0.21) preoperatively to 20/22 (SD +/- 0.13) postoperatively (P < 0.05). Spherical refractive error improved from -3.38 D (SD +/- 3.12) to -1.15 D (SD +/- 1.84); cylindrical refractive error improved from -3.75 (SD +/- 2.04) preoperatively to -1.21 (SD +/- 0.84) postoperatively (P < 0.05); average keratometry decreased from 49.50 D (SD +/- 1.64) preoperatively to 46.35 D (SD +/- 1.50) postoperatively. The changes remained stable to the 12-month follow-up. There was 1 case of anterior chamber perforation. There were 6 eyes that had ring exposure secondary to corneal thinning over the implants 3-6 months postoperatively, and a dense corneal infiltrate developed in 1 patient at 7 months postoperatively. CONCLUSIONS: The procedure appears to be effective in improving UCVA and BSCVA of patients with clinical keratoconus. In our small study group, however, there were significant (6/20) postoperative problems with regards to thinning and ring exposure.

Adult↗
PubMed2006

Ocular morbidity among children studying in private schools of Kathmandu valley: A prospective cross sectional study.

A prospective cross sectional study of students of two private schools was done and students were screened in detail. A total of 1816 students aged 5 to 16 years were evaluated, out of which 52.8% were males and 47.2 % were females. Among the total, 65.8% had no ocular abnormalities and 34.2% had some form of ocular disorders. Refractive error was the commonest problem seen accounting for 21.9% out of total, followed by infective disorders, which accounted for 7.2%, 3.5% of them were noted to have Orthoptic problem including various types of strabismus, 2.2% were color blind, 2.6% were found to have various other disorders. The prevalence of refractive error among private school children seems to be higher. Color blindness also seems to be prevalent among these children. This kind of school screening would help in detecting the eye problems timely and thus would reduce the ocular morbidity as well as prevent children from going blind unnecessarily.

Adolescent↗
PubMed1996

The prevalence of eye disease in elderly Bengalis in Tower Hamlets.

The prevalence of eye disease and uncorrected refractive errors in a group of 167 elderly members of the Bangladeshi community which resides in the London Borough of Tower Hamlets was studied. Of the subjects screened 24.6% were found to have a significant and potentially treatable cause of visual loss and a further 32.3% were visually handicapped through the presence of uncorrected refractive errors. A high prevalence (53.3%) of cataract was found in the elderly Bengalis. The high prevalence of eye disease in this ethnic minority group, has important implications for health service planning.

Aged↗
PubMed1997

Visual function following trabeculectomy: effect on corneal topography and contrast sensitivity.

PURPOSE: This study was to determine the role of changes in refractive error, contrast sensitivity, and corneal topography in transient changes in visual function following trabeculectomy. METHODS: We performed a prospective study evaluating these factors in 13 consecutive patients undergoing a standardized trabeculectomy. Preoperatively, and at 1, 4, and 12 weeks postoperatively, we measured best-corrected visual acuity, refractive error, and contrast sensitivity and analyzed computerized video-keratographic studies including estimated corneal visual acuity. RESULTS: One week postoperatively, best-corrected visual acuity decreased at least one line in 8 of 13 patients, whereas no eyes had decreased contrast sensitivity. Mean central corneal astigmatism increased 1.4 diopters along the surgical meridian. By 12 weeks, visual acuity returned to preoperative levels in all patients and the corneal topographic changes returned to within 1 diopter of preoperative values in 12 of 13 patients. Postoperative changes in estimated corneal visual acuity were similar to those in best-corrected visual acuity with no statistically significant difference. CONCLUSIONS: Corneal topographic changes appear to contribute to visual acuity reduction following trabeculectomy. In most cases this is transient with return to preoperative topography within 12 weeks.

Aged↗
PubMed2002

Prevalence of pigmented lens striae in a black population: a potential indicator of age-related pigment dispersal in the anterior segment.

PURPOSE: To determine the prevalence of pigmented striae of the anterior lens capsule, with or without associated glaucoma, in a black primary eye care population. METHODS: Over a 16-month period, five practitioners searched for pigmented lens striae (PLS) among consecutive patients who underwent pupillary dilation during routine eye care provided within the primary care service of an urban eye clinic in Chicago, Illinois. RESULTS: Meeting the inclusion criteria were 1608 blacks (mean age +/- SD, 40.9 +/- 23.7 years; range, 5 to 100; 1056 females, 552 males). Among the group, 29 (1.8%) subjects had PLS (mean age, 66.5 +/- 11.3 years; range, 33 to 88; 25 females, 4 males). PLS were bilateral 89% of the time. Sixteen of the 29 (55%) blacks had central corneal endothelial pigment dusting (14 bilateral), frequently creating a well-formed Krukenberg's spindle. Trabecular pigmentation varied among the PLS subjects from mild to heavy. Using multiple logistic regression, age (in years) (odds ratio, 1.05; 95% confidence interval, 1.02 to 1.07; p = 0.0003), female gender (odds ratio, 4.46; 95% confidence interval; 1.03 to 19.19; p = 0.045), and hyperopic refractive error (in diopters) (odds ratio, 1.35; 95% confidence interval; 1.09 to 1.67; p = 0.006) were significant predictors of PLS. CONCLUSIONS: PLS were present in about 1.8% (2.4% females, 0.7% males) of our black population, and they were frequently associated with other signs of intraocular pigment dispersion. Age, female gender, and refractive error were significant predictors for PLS. This is new information that is helpful for understanding a clinical sign that may be an indicator of age-related pigment dispersal within the anterior segment.

Adolescent↗
PubMed2002

Evaluation of E-optotypes as a screening test and the prevalence and causes of visual loss in a rural population in SW Uganda.

BACKGROUND: Few population-based eye surveys have been conducted in sub-Saharan Africa, limiting the quality of epidemiological information on visual loss from Africa. In the present paper, we describe the prevalence of visual loss in rural Uganda and the screening accuracy of E-optotypes when used by non-medical staff. METHODS: Residents of 15 neighbouring villages were screened for visual loss (<6/18 in either eye) using Snellen's E-optotypes. Individuals who failed were initially referred to an ophthalmic clinical officer (OCO), who retested visual acuity and subsequently referred to an ophthalmologist to determine the cause of visual loss. Subjects from two villages (248 individuals) who passed visual acuity screening were re-examined by the OCO to estimate the accuracy of the screening procedure. RESULTS: Of the 4076 adults (aged 13 years and over, 69.3% of the censused population) who participated, 191 (4.7%) failed the vision screening criteria and 648 (15.9%) had non-vision impairing conditions. The prevalence of visual loss was at least 3.9%: 0.4% had bilateral blindness, 1.6% had bilateral visual impairment, 0.7% had unilateral blindness and 1.2% unilateral visual impairment. Cataract was the leading cause for all categories of visual loss except bilateral blindness, for which suspected glaucoma was most frequent. Refractive errors were the second leading cause of bilateral and unilateral visual impairment. Based on one subject (0.4%) in the validation sample who was found to have low vision, we estimated the sensitivity and specificity of E-optotypes for detecting visual loss to be 93% and 99%, respectively. CONCLUSIONS: Cataract and refractive errors were responsible for most of the visual loss in rural Uganda. Snellen's E-optotypes provide a suitable cost-saving tool for conducting population-based eye surveys in sub-Saharan Africa.

Adolescent↗
PubMed1996

Ocular symptoms and signs associated with suramin sodium treatment for metastatic cancer of the prostate.

PURPOSE: Therapy with suramin sodium has been associated with photophobia, iritis, optic atrophy, and vortex keratopathy. We studied the ocular findings in patients who underwent treatment with suramin sodium for metastatic cancer of the prostate. METHODS: In a prospective study, 114 patients who underwent treatment with suramin sodium for cancer of the prostate had an ophthalmologic examination with two weeks of onset of treatment and two weeks after termination of therapy. Additional examinations were performed on patients who developed ocular symptoms during suramin sodium therapy. RESULTS: Nineteen (16.6%) of 114 patients developed ocular symptoms and signs while taking suramin sodium. Thirteen of these patients developed bilateral corneal epithelial whorllike deposits. In ten patients, the corneal deposits were associated with foreign body sensation and lacrimation. Symptoms in all of these patients resolved with topical lubricants. Three patients developed asymptomatic corneal deposits. Seven patients had blurred vision and were found to have a mean hyperopic shift in refractive error of 1.13 +/- 0.45 diopters (range, 0.75 to 2.00 diopters) that persisted throughout their treatment course. None of these patients had a decrease in best-corrected visual acuity. CONCLUSIONS: In this study, ocular symptoms and signs associated with suramin sodium were common but were not considered a dose-limiting toxicity. Hyperopic shift in refractive error is a previously unreported ocular finding in association with suramin sodium therapy.

Adult↗
PubMed2005

[Changes of eye refraction, corneal power and lens power during growth in emmetropia, myopia and hyperopia].

PURPOSE: The aim of this study was to evaluate changes of eye refraction, corneal power and lens power during growth in emmetropia, myopia and hyperopia. MATERIAL AND METHODS: We examined 183 children (363 eyes) aged 4 to 19 with emmetropia, myopia and hyperopia. All measurements were performed after cycloplegia with 1% tropicamidum. Total refraction and corneal power was examined with autokeratorefractometer. Then we used ultrasound biometer Ocuscan (Alcon, USA), to measure axial length of the eye. Lens power was calculated with use of SRK II formula. RESULTS AND CONCLUSIONS: Mean refractive error in whole group in the age of 4 was +2,86D and was gradually decreasing to reach OD in the age of 14. Between 4th and 14th years old, myopia increases slowly and then acceleration of this process was observed. In hyperopic eyes between 4th and 16th years old, refractive error decreases gradually and then stabilization was noted. Mean corneal power between 4th and 19th years old, decreased in emmetropia and myopia by 1.24D and 2.19D respectively, and increased by 0.38D in children with hyperopia. This changes took place before 10th years old. Mean lens power between 4th and 19th years old, decreased in emmetropia by 2.01 D, in myopia by 1.43D and in hyperopia by 1.78D. This changes took place before 12th years old.

Adolescent↗
PubMed1981

Contact lens effects on ametropia: a current example of the clinical trial.

This paper describes the basic features of an ongoing double masked, randomized, controlled clinical trial which studies the changes in corneal and visual function that result when contact lenses are fitted in a manner designed to alter myopic refractive error. Subjects are randomly allocated to either a treatment or control group. Corneal and visual changes resulting from wearing lenses of these designs are compared to the effects of wearing contact lenses fitted in a standard clinical manner. Comparative analysis of the treatment and control groups is based on (1) visual acuity, (2) refractive error, (3) corneal thickness, (4) endothelial cell density, (5) external eye health, (6) corneal curvature, (7) duration of effect, and (8) predictive factors such as ocular rigidity and corneal topography. Essential parts of the experimental design and some results from the first phase of the study are reported.

Clinical Trials as Topic↗
PubMed1999

Pars plana vitrectomy without scleral buckle for pseudophakic retinal detachments.

OBJECTIVE: To report the anatomic and visual results of primary pars plana vitrectomy (PPV) without scleral buckling to repair primary rhegmatogenous retinal detachments in pseudophakic eyes. DESIGN: Nonrandomized, prospective, comparative clinical trial. PARTICIPANTS: Two hundred eighty-three consecutive patients (294 eyes) with pseudophakia, peripheral retinal tears, and new rhegmatogenous retinal detachments were treated according to the surgery protocol. INTERVENTION: Patients underwent PPV with fluid-gas exchange and endolaser to repair the retinal detachment. Two hundred sixty-four patients (275 eyes) were followed from 6 months to 6 years and 8 months with an average follow-up of 19 months. MAIN OUTCOME MEASURES: Reattachment of the retina and visual outcome were compared to previously published studies. RESULTS: Of 97 eyes with a macula-attached rhegmatogenous retinal detachment, 88 eyes (91%) were reattached with a single operation, and of the 178 eyes with a macula-detached retinal detachment, 153 (86%) eyes were reattached with a single operation. In 241 (88%) of 275 eyes, the retina was reattached with a single operation, and in 265 (96%) of 275 eyes, the retina was ultimately reattached with subsequent operations. The median initial visual acuity was 20/300, and the median final visual acuity was 20/40. The rate of reattachment with one operation was similar for eyes with an anterior chamber intraocular lens (91%) and for eyes with a posterior chamber intraocular lens (88%). Refractive error measurements obtained in 81 eyes were essentially unchanged. The mean change in refractive error was -0.15 diopter. Seventeen eyes (6%) developed macular puckers requiring surgery, 46 eyes (17%) developed cystoid macular edema, and 6 eyes (2%) developed full-thickness macular holes. CONCLUSION: Primary PPV with fluid-gas exchange and laser is a safe, effective method to repair primary pseudophakic retinal detachments. The anatomic reattachment rate and the visual acuity obtained with this technique appear to be at least as good as those reported in the literature for scleral buckling, PPV with scleral buckling, and pneumatic retinopexy.

Fluorocarbons↗
PubMed2003

Recurrent lens binding and central island formations in a fast-responding orthokeratology lens wearer.

A 12-year-old girl with a history of fast myopia progression underwent advanced orthokeratology (ortho-k) treatment and suffered from recurrent lens binding and central corneal staining. The problem could not be fixed by lens fenestration and refitting with a less aggressive lens (three-zone ortho-k) design. After refitting with a lower target advanced ortho-k lens, these complications were no longer occurring, and the amount of power reduction was greater than expected considering the target designed for the refitted lenses. During the following 15 months of ortho-k lens wear, there was no clinically significant change to her refractive error. The patient and her parents were happy with the outcome, although the refractive error was not totally eliminated and she still needed to wear spectacles for clear vision. Possible etiologies of the complications are discussed.

Child↗
PubMed2002

Measuring the burden of ocular morbidity.

This hospital-based study highlights the spectrum of eye ailments in 35,273 patients who attended the Department of Ophthalmology at the B P Koirala Institute of Health Sciences, Eastern Nepal, during a 5-year period with varied clinical diagnosis. The attendance each year showed a progressive increase with a male preponderance. More than 13% of the patients were children. Cataract was the most common problem for which patients needed ophthalmic advice; diabetic and hypertensive retinopathy were frequent occurrences and infection was a common problem. Over 21% of the eyes examined had a refractive error: as high as 2.54% were amyblyopic caused by non-correction of refractive errors. Allergic conjunctivitis was frequently encountered. As shown by the magnitude of the problem, the existing eye care facilities must be enhanced and new strategies developed.

Adolescent↗
PubMedDate not supplied

Mesopic contrast sensitivity function after laser in situ keratomileusis.

PURPOSE: To evaluate contrast sensitivity under mesopic conditions in patients who have undergone uncomplicated bilateral laser in situ keratomileusis (LASIK) for myopia. METHODS: Best-corrected monocular contrast sensitivity was measured with the Stereo Optical F.A.C.T. chart at 1.5, 3, 6, 12, and 18 c/deg in 20 patients (20 left eyes) before and after bilateral LASIK (with the Nidek EC-5000 excimer laser and the Automated Corneal Shaper). Mean preoperative refractive error was -6.40 +/- 1.28 D (range -4.00 to -8.00 D) and postoperative mean refractive error was -0.41 +/- 0.45 D (range -0.75 to +0.50 D). Contrast sensitivity function was measured before and 6 months after surgery using four different chart luminances: 85, 5, 2.5, and 0.1 cd/m2, the first being a photopic level and the rest mesopic. Log contrast sensitivity values at each spatial frequency were used for statistical analysis and normalized values for graphical representation. RESULTS: Contrast sensitivity of postoperative LASIK eyes did not differ from preoperative values at a photopic level (85 cd/m2). However, under mesopic conditions (5 cd/m2 or less) a statistically significant reduction (P<.01) in contrast sensitivity was found at high spatial frequencies (12 and 18 c/deg), although no significant contrast sensitivity differences were observed at low and middle spatial frequencies (P>.01 for 1.5, 3 and 6 c/deg). CONCLUSIONS: LASIK induced significant reductions in contrast sensitivity under mesopic conditions only at high spatial frequencies, even though the photopic contrast sensitivity function was normal.

Adult↗
PubMed1994

Effects of optically induced blur on the refractive status of young monkeys.

In each of eight rhesus monkeys, one eye was defocused with a -9 D contact lens beginning before 1 month of age for periods of 2-3 months. At the end of the rearing period, interocular comparisons showed that one subject had developed a relative axial myopia (3.0 D), however, five monkeys had developed a relative axial hyperopia (2.0-3.5 D). After discontinuing the contact-lens rearing procedure, the induced refractive errors diminished over time in all subjects. These results indicate that the defocus threshold for form-deprivation myopia is relatively high and that substantial levels of optical defocus which do not exceed this threshold typically produce axial hyperopia. The recovery data suggests that monkeys have an emmetropization mechanism which is sensitive to optical defocus, but the failure of this mechanism to compensate for the refractive errors simulated during the lens-rearing procedures suggests that this mechanism has a limited operating range.

Animals↗