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We describe a case of the SHORT syndrome and compare it with previously published cases. This six-year-old girl shows nearly all the typical manifestations reported in patients with the SHORT syndrome, including lipoatrophy, minor facial anomalies, Rieger anomaly, and short stature. However, she also suffers from high hyperopia and astigmatism associated with poor visual acuity.
Changes in keratometer readings were measured in 87 patients, wearing hydrophilic contact lenses for three to more than eighteen months. Twenty-four eyes in the group had an increase of +0.75 or more in the keratometer readings, which invariably involved the vertical reading and was often associated with a distortion of the mire reflex. The change was high as +2.75 diopters. If greater than +1.00 diopter, it was associated with decreased visual acuity with forward correction and with the hydrophilic contact lenses. All but one of the patients who showedchanges of greater than +0.75 diopters over their baseline keratometer readings, were wearing their lenses on an average of 14-16 hours a day. The keratometer readings reverted to the baseline levels with a loss of the distrotion, if the patient reduced the wearing time to less than 12 hours daily. We believe that a maximum average daily wearing time of 12 hours is the safety limit required to minimize the development of induced corneal astigmatism.
PURPOSE: The purpose of this study was to evaluate changes of the corneal curvature as a result of linear incisions with excimer laser and also to evaluate durability of the achieved effect, including the changes in visual acuity, topographic maps of the corneal curvature and keratometric changes at the location of keratoconus 2, 4, 8, 16, 24 weeks postoperatively. MATERIAL AND METHODS: At the First Department and Clinic of Ophthalmology, Silesian Medical School in Katowice, 294 patients went through ophthalmological examinations. 164 patients (187 eyes) with the III degree of keratoconus according to the Amsler scale, including 69 women (77 eyes) and 95 men (110 eyes), were classified for the excimer laser surgery with the method of linear, corneal incisions with MEL-60 (Aesculap-Meditec). The eyes did not tolerate contact lenses at all or because of peripheral location of the keratoconus. The patients were from 16 to 60 years of age (the mean age was 27.9 years). RESULTS: According to the statistical results, there were no difference between the effects of treatment between men and women. Correlation between the results of the surgery and the patients age showed that the latter did not have any effect on the final result. Lack of correlation between the height of the absolute corneal curvature at the keratoconus and the achieved change after the surgery was reported, thus changes of the corneal curvature parameters do not depend on its parameters before the surgical procedure. Absolute visual acuity of patients was improving and reached maximally 0.252 of the unit. As a result of the single surgery, the maximum change of keratometric values was 4.949 D, and the minimum was 3.611 D. In the case of the secondary surgery, the maximum keratometric value at the axis of the incision was 8.55 D and the minimum one was 7.101 D. CONCLUSION: To sum up, we can say that the favourable effect of decreasing the irregular corneal astigmatism with the method of linear laser fotoablations was maintained throughout the whole observation period, which allowed to shift in time planned corneal transplantation.
PURPOSE: The purpose of this study was to evaluate changes of the corneal curvature as a result of excimer laser ablation using the TOSCA and TSA system. MATERIAL AND METHODS: At the First Department and Clinic of Ophthalmology, Silesian Medical School in Katowice, 8 patients (8 eyes) with the II and III degree of keratoconus according to the Amsler scale, including 4 women (4 eyes) and 4 men (4 eyes), were classified for the excimer laser surgery with the method of PRK with TOSCA program and TSA system with MEL 70 G-Scan (Asclepion-Meditec). The eyes did not tolerate contact lenses at all or because of peripheral location of the keratoconus. The patients were from 18 to 42 years of age (the mean age was 25.8 years). The observation period was 4 weeks. RESULTS: According to the statistical results lack of correlation between the height of the absolute corneal curvature at the keratoconus and the achieved change after the surgery was reported. The improvement of patients absolute visual acuity was improving and reached 0.2 of the unit. CONCLUSION: To sum up, we can say that the favourable effect of decreasing the irregular corneal astigmatism with the method of laser fotoablations with topography-controlled system was maintained throughout the whole observation period, which probably allowed to shift in time planned corneal transplantation.
Heritability estimates for corneal power were found to be high and similar for two populations which differed in their incidence of esotropia. This similarity suggest (1) that genetic differences for corneal power do not contribute to the difference in heritability for spherical refractive error reported for these populations and (2) that this character is not a critical variable contributing to the pathophysiology of esotropia. Heritability estimates for corneal astigmatism were, in most cases, rather low. The pattern of population and sex differences among heritability estimates was consistent with those previously reported for cylindrical refractive error. These population differences in heritability suggest that they contribute to population differences found for cylindrical refractive error.
A unique clinical case is presented: LASIK in a 12-year-old child for correction of posttraumatic corneal astigmatism after penetrating wound of the eye and extraction of traumatic cataract with IOL implantation. The patient was observed for 3 months postoperation.
OBJECTIVE: To compare the changes in the values and directions of surgically induced astigmatism (SIA) after phacoemulsification with three different-sized scleral tunnel incisions and to evaluate their clinical results. METHODS: The patients were divided into three groups; the length of the scleral tunnel incision was 3.2, 5.5 and 7.0 mm respectively in A, B and C groups. Keratometry measurements were obtained preoperatively, at postoperative 1 week, 1 month and 6 months respectively. SIAs were analyzed by "Cravy vector method". The mean SIA and uncorrected visual acuity were compared among the groups up to 6 months postoperatively. RESULTS: Eyes in A group displayed significantly less mean SIA and better uncorrected visual acuity than B and C groups at 1 week postoperatively (P < 0.05), but there were no significant differences between any groups at 1 month, 3 months and 6 months postoperatively (P > 0.05). There were no significant differences in the mean SIA and uncorrected visual acuity between B and C groups throughout the whole study period (P > 0.05). CONCLUSIONS: SIAs in eyes of 3.2 mm incision group of phacoemulsification are less and more stable; a better and quicker rehabilitation of uncorrected visual acuity can be obtained in the early postoperative period.
With increasing age a corneal, inverse astigmatism may develop, leading to an unequal projection upon the retina depending on the different angles of view. Fine details, like fissures in a X-ray photograph, will only be recognized in turning the photograph for 90 degrees.
Performed were 78 operations of correction of astigmatism by the method of linear incision of the cornea by means of an excimer laser. In dependence of the degree of the error two or four incisions were executed. The period of observation amounted 3 to 22 months. Improvement of refraction was obtained in the amount of 0.5 to 9.0 dioptres in relation to the initial one.
The authors made a statistical study of the refraction and corneal topography in 21 patients who had penetrating grafts for keratoconus performed by the same surgeon one year or more previously. They used various criteria among which the following were important: -- the importance of Javal ophthalmometry to determine the astigmatism for prescription; -- good visual results; -- the recording of significant corneal deformities during the topographical studies.
One hundred twelve unilateral cataract extraction patients were randomly assigned to receive either a one-piece Staar Model AA-4203 silicone intraocular lens (IOL) implanted through a 3.2-millimeter incision, or a one-piece polymethylmethacrylate IOL implanted through a 6.0-millimeter incision. Follow up was 96% at 1 day postoperatively, 90% at 3 months, and 70% at 1 year. Fifty-three percent of the eyes that received a smaller incision could see 20/40 or better uncorrected at 1 day, as compared with 19% of the eyes that received a 6-millimeter incision (P < .01). At 3 months, significantly more smaller-incision eyes could still see 20/40 or better (P = .03). The smaller-incision eyes also had significantly less surgically-induced astigmatism at both 1 day (P < .01) and 3 months (P = .02), and had significantly less flare (P < .01) and cellular reaction (P = .04) at 1 day.
We present a patient who underwent bilateral radial keratotomy (RK) followed by a bilateral revisional RK for undercorrection. After the second procedure, the patient had a severely flattened left cornea, with marked hyperopia and irregular astigmatism. The right eye, however, remained myopic, causing extreme anisometropia. We hypothesize that the different results in these two eyes may have been due to a critical number of damaged left corneal stromal fibers. Patients undergoing revisional RK or requiring additional incisions may be at increased risk for such a complication.
BACKGROUND: The purpose of our study was to determine if the development of refractive errors night be associated with exposure to light emitted by incandescent or fluorescent lamps. MATERIAL/METHODS: 3377 students from elementary schools, junior high schools and high schools were examined, aged 6-19 years. Visual acuity was measured, and retinoscopy was performed after cycloplegia. The parents of all students examined completed a questionnaire concerning the child's exposure to light emitted by incandescent or fluorescent lamps before the age of two. The data was analyzed using the chi-squared test. RESULTS: Sleeping till the age of two with a room light turned on leads to an increase in the occurrence of myopia (P<0.01). It was also found that light emitted by fluorescent lamps leads to more frequent occurrence of astigmatism (P<0.01). CONCLUSIONS: Disturbance of the daily light/dark cycle over the time during which refraction develops may disrupt emmetropization and lead to refractive errors.
Anisometropic myopia and myopic astigmatism are very often refractive error in children. Suitable correction of different vision defects in children might prevent the consequences of amblyopia and lack of development of binocular vision. This article presents the effectiveness of correction in myopia and myopic anisometropia using laser method such as PRK, LASEK and LASIK. It is the literature review.
Corneal incision in cataract surgery will produce a large degree of astigmatism greater than that produced in cataracts operated on by the classical methods. The position of the incision and the suture material (nylon) are responsible. The authors have attempted a statistical study of this difference, comparing modern and classical methods, referring for the latter to previous work.
The impact produced by incisions of 2 examined types on the corneal refraction was studied in 40 patients (40 eyes) shared between 2 groups according to an incision type. 5 mm tunnel self-sealing incisions of 2 types, i.e. temporal corneal one longer by 3 mm, and upper linear sclerocorneal one stabilized by horizontal suture, were made use of. The obtained refraction was evaluated on week 1 and then in 1 and 3 months after surgery. Group 1 (surgical approach: 5 mm linear sclerocorneal tunnel incision): the mean value of induced astigmatism made 0.68 D during the initial 3 postoperative days, 0.62 D in 1 month after surgery and 0.73 D in 3 months after surgery. Group 2 (surgical approach: 5 mm temporal corneal tunnel incision): the above value made 1.1 D during the initial 3 postoperative days, 0.7 D in one month after surgery and 0.52 D in 3 months.
BACKGROUND: A mechanical model of the human cornea is proposed and employed in a finite element formulation for simulating the effects of keratotomy on the cornea. METHODS: The formulation assumes that the structural behavior of the cornea is governed by the properties of the stroma which is modeled as a thick membrane. The tensile forces in the cornea are resisted by the collagen fibrils embedded in the ground substance of the stromal lamellae. When the stromal lamellae are cut, as in keratotomy, it is assumed that they no longer carry any tensile forces, and the forces in the cornea are then resisted only by the remaining uncut lamellae. A constitutive model, which represents the anisotropy and inhomogeneity in the membrane rigidity induced by the incisions, has been employed in a geometrically nonlinear finite element membrane formulation for small strains with moderate rotations. This preliminary model is restricted to linear material behavior with no time dependency. RESULTS: A number of numerical examples are presented to illustrate the effectiveness of the proposed constitutive model and the finite element formulation for computing the immediate postoperative shift in corneal power resulting from radial, astigmatic, and hexagonal keratotomy. Surgical changes computed using the proposed model compare well with surgical corrections predicted by expert surgeons. CONCLUSIONS: The proposed computational model of the cornea and the effects of surgical procedures on it is based on a number of important simplifying assumptions regarding the mechanical properties and structure of the corneal tissue at the ultrastructure level. The encouraging results found with present model suggest that further development and refinement will be useful.
Soft toric contact lenses are a good alternative for the optical correction of astigmatism. They provide a wide visual field, quick adaptation process, negligible aniseikonia, together with enhanced comfort and reduced incidence of complications introduced by the lenses for frequent replacement. Still practitioners do not recommend them proactively and the satisfaction obtained by the patients is not high enough. This paper presents two recent studies that investigate the opinions of specialists and contact lens wearers and introduce a new contact lens, with an original design, born after 30 years of domination of only 2 modalities of rotational stabilization: prism ballast and dual thin zones. The lens is manufactured using a silicon-hydrogel material of 2-nd generation that provides sustained comfort and better oxygenation.