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At least 1,477 records · Page 82Linked to original sources
PubMed1991

Prevalence and association of asteroid hyalosis with systemic diseases.

We performed a cross-sectional study of 12,205 patients, which identified 101 patients (0.83%) with asteroid hyalosis. These patients were examined for associated systemic and ocular conditions. Diabetes mellitus was found in 29 of the patients with asteroid hyalosis (29%), as compared to ten of 101 (10%) control subjects (P = .0007). An increased prevalence of systemic arterial hypertension (61 of 101 [60%] patients with asteroid hyalosis compared with 29 of 101 [29%] control subjects; P = .0001) and atherosclerotic vascular disease (30 of 101 [30%] patients with asteroid hyalosis compared with 13 of 101 [13%] control subjects; P = .006) was also discovered in the asteroid hyalosis group. Additionally, patients with asteroid hyalosis were found to be more hyperopic than control subjects (P = .009).

Adult↗
PubMed1995

Refractive changes at extreme altitude after radial keratotomy.

PURPOSE: We studied the effects of altitude on four corneas that had undergone radial keratotomy and four normal corneas exposed to increasing elevation during a high-altitude excursion. METHODS: We measured visual acuity, cycloplegic refraction, keratometry, and intraocular pressure at sea level and after 24-hour exposure to 12,000 and 17,000 ft. RESULTS: We observed a significant increase in spherical equivalence (hyperopic shift) in radial keratotomy eyes exposed to altitude as compared to controls (P < .0001). The average change in spherical equivalent cycloplegic refraction from sea level to 12,000 ft was 1.03 +/- 0.16 diopters and from sea level to 17,000 ft was 1.94 +/- 0.26 diopters. We also observed a significant decrease in keratometry values at altitude as compared with control corneas (P < .0001). The average change in keratometry from sea level to 12,000 ft was 0.59 +/- 0.19 diopter and from sea level to 17,000 ft was 1.75 +/- 0.27 diopters. CONCLUSIONS: Although the specific origin of these changes is open to question, we hypothesize that hypoxic corneal expansion in the area of the radial keratotomy incisions may lead to central corneal flattening and a hyperopic shift in refractive error. The cornea that has undergone radial keratotomy appears to adjust constantly to changing environmental oxygen concentration, producing a new refractive error over a period of 24 hours or more. Additional study is required to identify with certainty the specific origin of the hyperopic shift at high altitude.

Adult↗
PubMed1990

A refractive and histopathologic study of excimer laser keratectomy in primates.

Using a 193-nm excimer laser, we produced wide-area, refractive keratectomies on 18 cynomolgus monkey corneas and followed them up for up to 18 months. All corneas developed some subepithelial haze by one month. Electron microscopy disclosed epithelial thickening, absence of Bowman's layer, and subepithelial activated fibroblasts surrounded by disorganized collagen. By six months, the haze faded to a variable degree, the epithelium regained normal thickness, and the collagen was more organized. Persistent corneal haze at 12 months in some corneas correlated with electronlucent spaces in the subepithelial zone. Corneas were 90 microns thinner centrally two weeks after myopic ablation, but returned to preoperative thickness by six months. Myopic flattening and hyperopic steepening of 6 diopters were targeted, and over 7 diopters of each were achieved initially. Regression of induced curvature stabilized over several months. At 18 months, 4.4 diopters of myopic flattening and 5.2 diopters of hyperopic steepening remained.

Animals↗
PubMed1980

Refractive power of premature children at infancy and early childhood.

We evaluated the refraction of 198 children born prematurely with birth-weights of 2,000 g or less, without any ocular disease. Between the ages of 6 months to 3 1/2 years these children had a mild hypermetropia. The refractive error did not change between the ages of 6 months and 3 1/2 years. The refraction of the prematurely born children was similar to that found in children born at full term.

Age Factors↗
PubMed1980

Early-onset accommodative esotropia.

Twenty-one patients had esotropia diagnosed before age 12 months. In all of these patients esotropia was eliminated, at least initially, by antiaccommodative therapy consisting of either full hypermetropic spectacles or miotics, or both. Clinical findings evaluated in these patients were comparable to similar clinical factors studied in a larger series of patients with accommodative esotropia, most with onset after 12 months of age. In approximately 50% of these patients early-onset accommodative esotropia deteriorated to a nonaccommodative esotropia that required surgery despite aggressive antiaccommodative therapy. All but one of the surgically treated patients continued to need hypermetropia spectacles postoperatively to maintain alignment.

Accommodation, Ocular↗
PubMed1990

Accommodative convergence in hypermetropia.

We compared the clinical characteristics of esotropic, hypermetropic children whose strabismus was fully corrected with spectacles (refractive accommodative esotropia) with those who remained orthotropic (that is, had no manifest strabismus on the cover test) in the presence of uncorrected hypermetropia. In addition to a standard ophthalmologic and orthoptic examination, we determined the stimulus accommodative convergence/accommodation (AC/A) ratio by using the gradient method over a range of 6 diopters, the near point of accommodation, and random dot stereopsis. Hypermetropic patients without esotropia or significant esophoria were found to have a low AC/A ratio in contrast to those patients with refractive accommodative esotropia. This finding explains why esodeviations may be absent in some hypermetropic patients with uncorrected vision. We found a high prevalence of abnormally low near points of accommodation and defective or absent stereopsis in both groups of patients.

Accommodation, Ocular↗
PubMed1998

Lasso procedure to revise overcorrection with radial keratotomy.

PURPOSE: To report three patients who underwent the lasso procedure to revise overcorrection with radial keratotomy. METHODS: Case report and review of the literature. RESULTS: Four eyes of three patients who had undergone radial keratotomy with resultant hyperopic overcorrection underwent a lasso procedure. Before the procedure, average cycloplegic refraction spherical equivalent was +3.656 +/- 1.352 diopters, and average manifest refraction spherical equivalent was +2.250 +/- 0.621 diopters. A 10.0 monofilament nylon suture was placed in a circumferencial manner through the corneal stroma and overlapping the old radial keratotomy incisions. At 1 month postoperatively, best-corrected visual acuity was 20/20 in all four eyes, with average cycloplegic refraction spherical equivalent +0.438 +/- 1.423 diopters and average manifest refraction spherical equivalent -0.156 +/- 1.147 diopters. Mean delta cycloplegic refraction spherical equivalent was 3.219 +/- 1.724. CONCLUSIONS: The lasso procedure provides an immediate solution for symptomatic overcorrected hyperopic eyes after radial keratotomy. Predictability and long-term stability necessitate further follow-up.

Adult↗
PubMed1999

Central bump-like opacity as a complication of high hyperopic photorefractive keratectomy.

PURPOSE: A new complication is reported in association with high hyperopic excimer laser photorefractive keratectomy. METHODS: One thousand consecutive eyes were treated with a Meditec MEL-60 excimer laser (Meditec Inc, Heroldsberg, Germany) for hyperopic refractive error between +1 diopters and +7 diopters. RESULTS: Three eyes with high hyperopic corrections between +5 and +6 diopters had a central, round bump-like subepithelial scar develop 1 month after hyperopic photorefractive keratectomy, which reduced the uncorrected and spectacle-corrected visual acuity. CONCLUSION: Central bump-like opacity is a new, visually significant complication of unknown origin associated with high hyperopic photorefractive keratectomy. Possible causes of this complication include drying and edema of the cornea as a result of prolonged exposure, interruption of the peripheral superficial nerve plexus affecting the central anterior stroma, and abnormal epithelial or tear film function resulting from excessive central steeping.

Adult↗
PubMed2000

Lens minibar to facilitate refraction.

PURPOSE: To describe a lens minibar that facilitates refraction. METHODS: Ten lenses of 1-diopter increment were glued to form a hyperopic minibar (range from +1.00 to +5.00) and a myopic minibar (range from -1.00 to -5.00), the size of a credit card. RESULTS: The lens minibar allowed expedited refraction in children and in consultations that took place outside the clinic. CONCLUSION: The lens minibar is an inexpensive, small, lightweight tool that facilitates quick refraction.

Child↗
PubMed2001

Laser in situ keratomileusis to correct myopia, hypermetropia and astigmatism after penetrating keratoplasty for keratoconus: a series of 27 cases.

BACKGROUND: Excimer laser treatment has been shown to be effective and safe in correcting anisometropia following penetrating keratoplasty (PKP). In this report we review our experience with excimer laser in situ keratomileusis (LASIK) to correct refractive myopia, hypermetropia and astigmatism in patients who had undergone PKP for keratoconus. METHODS: We reviewed the records of 22 patients (27 eyes) who had undergone LASIK to correct myopia, hypermetropia or astigmatism, in simple or combined forms, following corneal transplantation for keratoconus. LASIK was performed at a hospital in Curitiba, Brazil, between September 1998 and February 2000. The eyes were classified into two groups: those with a negative spherical equivalent and those with a positive spherical equivalent. LASIK was performed using the Moria LSK microkeratome and the Nidek EC-5000 excimer laser. RESULTS: The mean length of follow-up was 9.52 months for the 23 eyes with myopia and 5.75 months for the 4 eyes with hypermetropia. The mean refractive spherical equivalent in the myopic eyes was -5.27 (standard deviation [SD] 1.91) dioptres before LASIK and -0.45 D (SD 1.68 D) at the last follow-up visit. The corresponding values in the eyes with hypermetropia were +5.18 D (SD 1.46 D) and + 1.18 D (SD 0.94 D). The rate of regression of astigmatism in the myopic eyes was 76%. After surgery 18 (78%) of the myopic eyes and all the hypermetropic eyes had an uncorrected visual acuity of 20/40 or better. The best spectacle-corrected visual acuity was better than 20/25 in 22 (95.7%) of the myopic eyes and all the hypermetropic eyes. One eye lost 1 line of best spectacle-corrected Snellen visual acuity, and one eye lost 6 lines secondary to epithelial ingrowth. Wound dehiscence, intraoperative flap complications, graft rejection or other complications did not develop in this series. INTERPRETATION: In this series, LASIK proved to be relatively safe and effective in correcting refractive errors after PKP for keratoconus.

Adult↗
PubMed2003

Presbyopia complicating pre-existing strabismus.

BACKGROUND: Presbyopia may affect pre-existing sensory adaptations or aggravate previously asymptomatic heterophoria. We describe the presentation, underlying problem and management of 11 patients with pre-existing strabismus or heterophoria who presented with new symptoms of double vision attributable to presbyopic change, an association not previously reported. METHODS: Patients with new strabismic symptoms attributable to presbyopia were recruited prospectively over a 1-year period. RESULTS: The 11 patients had had a recent decrease of accommodative amplitude that resulted in blurred vision at near with a breakdown of pre-existing heterophoria (2 patients), alteration of fixation pattern (6 patients), symptomatic alternating fixation (2 patients) or intolerance to correction owing to restrictive strabismus (1 patient). INTERPRETATION: At the onset of presbyopia, symptoms may be varied and subtle. Ophthalmologists and orthoptists should carefully determine the exact nature of the symptoms. Any pre-existing fixation pattern should then be established from the history, old photographs or suppression characteristics. Refractive or surgical management should be aimed at returning the patient to his or her long-standing sensory adaptation. Other important issues, such as incomplete correction of hypermetropia by refractive surgery and problems using bifocals with vertical restrictive strabismus, should be noted.

Accommodation, Ocular↗
PubMedDate not supplied

The change in ocular refractive components after cycloplegia in children.

PURPOSE: To study the change in ocular refractive components after cycloplegia in children. METHODS: Anterior chamber depth, lens thickness, vitreous chamber length, and ocular axial length were measured in 135 Chinese children (270 eyes) before and after cycloplegia. The corneal curvatures of 136 selected eyes were studied before and after cycloplegia with a computerized video keratoscope. RESULTS: Anterior chamber depth increased (P <.001) while both lens thickness and vitreous chamber length decreased (P <.001) significantly after cycloplegia regardless of the refractive state. However, axial length increased in hyperopic eyes (P =.027) but decreased in myopic eyes (P =.008) after cycloplegia. Mean corneal power of zones 3 mm (MD3, P =.009) and keratometer K1 readings increased (P =.025) in hyperopic eyes, while MD3 (P =.033), K1 (P =.039) and K2 (P =.003) readings decreased in myopic eyes significantly after cycloplegia. Similarly, mean corneal power of zones 5 mm and 7 mm in myopic eyes decreased dramatically (P <or=.001). In both hyperopic and myopic eyes, there was significant difference (P <.001) in the mean value of the upper and lower half of the vertical meridian, as well as the medial and lateral half of the horizontal meridian, respectively. CONCLUSIONS: Cycloplegia has a great influence on various refractive components in children. There is asymmetry of the corneal surface within the same horizontal or vertical meridian.

Accommodation, Ocular↗
PubMed2003

Refractive abnormalities in childhood.

The knowledgeable pediatrician can make a significant contribution to the management of refractive errors by aiding in the early recognition of abnormalities, making appropriate referrals, and reinforcing the ophthalmologist's recommendations to the family. If this article has focused the reader's attention and caused a few rays of light to fall on an important subject, it has achieved its purpose.

Accommodation, Ocular↗