Myopic Changes Research Articles

Optic disc of the myopic eye: relationship between refractive errors and morphometric characteristics

Because the optic disc in myopic eyes is different from a normal optic disc, there are many difficulties in examining the optic discs of myopic eyes. To study optic disc change due to myopia, we performed a morphometrical study of stereophotographs of 61 men, 109 eyes, who had no glaucoma history. The range of refractive error was from +0.75 diopter to -12.75 diopter, and all subjects had intraocular pressure below or equal to 21 mmHg. According to the increase in the myopic degree, the temporal slope of the disc cup was significantly decreased, but the ratio of the vertical disc diameter (VDD) to the horizontal disc diameter and the ratio of the width of peripapillary atrophy (PPA) to the VDD were significantly increased. The above results suggests that in high myopia the optic disc was tilted and the rim-cup border was indistinct and there are some problems in the estimation of the morphometric parameters. Also in evaluation of the PPA of myopic glaucoma patients, there may be some difficulty in deciding whether it is due to myopic change or glaucomatous damage.

The amelioration of myopia using biofeedback of accommodation: a review

The purpose of this review is to give an account of the issues raised by reports that myopia can be treated by operant conditioning or biological feedback. Devices are available that provide auditory feedback of accommodative state such that variation in tone frequency provides a means by which the patient can monitor his or her ability to induce changes in accommodation response, the task thus being to change the pitch of the tone in a direction corresponding to a more distant far point. The aim of a training programme is to reinforce and establish control over the accommodative response by a process akin to operant conditioning and subsequently to transfer the skill to normal visual environments such that a manifest reduction in myopia becomes apparent. Although there are reports that the technique can induce a reduction in myopia by up to 3 D the findings are of limited value owing to the lack of objective data, for example pre- and post-training cycloplegic refraction. The pre- and post-training measures of subjective letter acuity used by many studies are, with repeated trials, particularly vulnerable to individual differences in the ability to learn how to discriminate and interpret blurred images. The review concludes that more comprehensive clinical trials are needed before accommodation biofeedback can qualify as an established method of clinical treatment of myopia. The trials should be designed to encompass the following issues: the characteristics of a feasible physiological model linking accommodation and myopia development; the rationale with regard to patient selection; the technical performance of the optometer employed; the characteristics of the control group used; the criteria for assessment of myopic change; the transfer of training to performance in normal visual environments; the economic viability of the programme of training and equipment; and the skill, training and knowledge of the clinician implementing the training programme.

The amelioration of myopia using biofeedback of accommodation: a review

The purpose of this review is to give an account of the issues raised by reports that myopia can be treated by operant conditioning or biological feedback. Devices are available that provide auditory feedback of accommodative state such that variation in tone frequency provides a means by which the patient can monitor his or her ability to induce changes in accommodation response, the task thus being to change the pitch of the tone in a direction corresponding lo a more distant far point. The aim of a training programme is to reinforce and establish control over the accommodative response by a process akin lo operant conditioning and subsequently to transfer the skill to normal visual environments such that a manifest reduction in myopia becomes apparent. Although there are reports that the technique can induce a reduction in myopia by up to 3 D the findings are of limited value owing to the tack of objective data, for example pre- and post-training cycloplegic refraction. The pre- and post-training measures of subjective letter acuity used by many studies are, with repeated trials, particularly vulnerable to individual differences in the ability to learn how to discriminate and interpret blurred images. The review concludes that more comprehensive clinical trials arc needed before accommodation biofeedback can qualify as an established method of clinical treatment of myopia. The trials should be designed to encompass the following issues: the characteristics of a feasible physiological model linking accommodation and myopia development; the rationale with regard to patient selection: the technical performance of the optometer employed; the characteristics of the control group used; the criteria for assessment of myopic change: the transfer of training to performance in normal visual environments; the economic viability of the programme of training and equipment: and the skill, training and knowledge of the clinician implementing the training programme.

The Relationship of Visual Acuity, Refractive Error, and Pupil Size After Radial Keratotomy

To better define the relationship between residual refractive error, uncorrected visual acuity, and pupil diameter, we compared 42 eyes that had an eight-incision radial keratotomy according to the Prospective Evaluation of Radial Keratotomy Study protocol with 42 matched control eyes. The parameters measured were best corrected visual acuity, uncorrected visual acuity, and the change in cycloplegic refraction with enlarging pupil diameter. The best corrected visual acuity was 20/16 in both the radial keratotomy and control groups, but the variability (SD) was higher in the radial keratotomy group. The average uncorrected visual acuity was 0.35 (35%) better in the radial keratotomy group, but the variability was 1.77 times higher. Change in refraction with dilation occurred in 9% of the controls and 36% of the radial keratotomy patients, indicating a significant difference (P = .002). The change in refraction with dilation in the eyes with radial keratotomy was almost equally split between a hyperopic change (17%) and a myopic change (18%), which was much different than in the control eyes, only 2% of which changed in a hyperopic direction and 7% in a myopic direction. The radial keratotomy patients with a myopic change had the best uncorrected visual acuity, indicating that positive spherical aberration yielded the best aspherical surface for uncorrected visual acuity.

CAUSATIVE FACTORS OF RETINAL DETACHMENT IN MACULAR HOLES

Two hundred nine macular holes of both pathologic myopia and idiopathic senile type were statistically analyzed to find out which factors cause retinal detachment in eyes with macular holes. The incidences of retinal detachment were as follows: 97.6% in myopia over -8.25 D, 67.7% in myopia between -8.0 and -3.25 D, and 1.1% in eyes under -3.0 D; 100% in widespread chorioretinal atrophy, 90.6% in spotty or lineal chorioretinal atrophy, 64.3% in myopic tigroid fundus, and 0% in eyes without myopic tigroid or atrophy; 96.0% in eyes with posterior staphyloma and 8.2% in eyes without it; 56.4% in posterior vitreous detachment [PVD] (+) eyes, 53.3% in PVD(+/-) eyes, and 51.9% in PVD(-) eyes. The statistically significant (P less than 0.05) factors that caused retinal detachment were refractive error, myopic chorioretinal change, and posterior staphyloma. There was no statistically significant difference regarding PVD.

Effect of Corneal Hydration and Intraocular Pressure on Keratometric Power after Experimental Radial Keratotomy

Persistent diurnal fluctuations in vision are common after radial keratotomy (RK), associated with a myopic change in refraction and keratometric power as the day progresses. A possible relation between keratometric power and either intraocular pressure (IOP) or corneal hydration was investigated in a cadaver eye model. First, keratometric power was measured before and after RK while IOP was varied from less than 0.5 to 20 mmHg. A nonlinear relation was found; in particular, changes in IOP in the physiologic range had no effect on keratometric power after RK. In a second set of experiments, keratometric power was measured after RK as the dehydrated corneas were gradually hydrated with balanced salt solution. After RK, keratometric power decreased markedly as corneal hydration increased (0.33 diopters [D] per 10-μm increase in thickness). The keratometric power of control corneas was not affected by changes in IOP or hydration. The author concludes that diurnal fluctuations in refraction after RK are probably caused by diurnal fluctuations in corneal hydration rather than changes in IOP.

Postoperative Refractive Changes in Children With Congenital Esotropia: A Preliminary Study

ABSTRACT A transient myopic inclination was found 2 months postoperatively in 23 children who had undergone surgery for congenital esotropia. Neither the age of the children at the time of surgery nor the length of muscle recession/resection influenced these refractive myopic changes. Early postoperative refractive correction with periodic follow-up is essential in preventing amblyopia. In 21 of the 23 children, visual acuity was 6/10 or better at last examination.

Cataract: the relation between myopia and cataract morphology.

The association between high myopia and cataract is already well established and an association between simple myopia and cataract has been suggested, but it has not been clear to what extent the myopia precedes the cataract or is the result of it. The present study compares the refraction of a group of 100 British patients at the time of first presentation with cataract in whom the refraction was also known four years previously, with a group of matched controls in whom the refraction was also known four years previous to presentation. The study shows that simple myopia does not appear to predispose to cataract. It is the development of the cataract itself, in particular nuclear sclerosis, which causes the refractive change towards myopia. The myopic change precedes the development of cataract, and patients over the age of 55 showing a myopic change in refraction have a very high probability of developing nuclear sclerotic cataract. The healthy aging eye and eyes with cortical cataract or subcapsular cataract, but without nuclear sclerosis, continue to show a gradual hypermetropic change with time.

Refractive error change at the United States Air Force Academy--class of 1985.

A retrospective study was conducted at the United States Air-Force Academy (USAFA) to determine the incidence and change in refractive error over a 2.5-year period between the entrance and third academic year physical examinations. For all 994 eyes (497 cadets aged 17 to 21 years) at entrance, there were 37.3% hyperopes, 18.5% emmetropes, and 44.2% myopes of -0.25 D or more, by spherical equivalent (SPEQ). A significant (p less than 0.001) mean SPEQ change of -0.18 D, -0.21 D, and -0.57 D occurred for the hyperopic, emmetropic, and myopic eyes, respectively, over this period. A myopic change of -0.25 D or more was seen in 47.7%, 41.3%, and 74.0% of the hyperopic, emmetropic, and myopic eyes, respectively, with a clinically significant myopic shift of -0.50 D or greater seen in 21.3%, 25.0%, and 55.1% of these refractive error types, respectively. Myopia progression was derived separately from those eyes showing any amount of myopic shift (greater than or equal to -0.12 D), and was -0.42 D, -0.52 D, and -0.75 D for the hyperopic, emmetropic, and myopic eyes, respectively. There was a higher incidence and rate of myopia increase in the higher refractive errors, whether hyperopic or myopic. These findings suggest that 17- to 21-year-olds are not as safe from a myopic change as thought previously, particularly during an intensive educational program.

Features of a Syndrome With Congenital Cataract and Hypertrophic Cardiomyopathy

We studied 12 patients from six unrelated families with a syndrome that has an autosomal recessive pattern of inheritance and can be diagnosed from clinical, histologic, and biochemical characteristics. The four major symptoms are congenital cataract, hypertrophic cardiomyopathy, mitochondrial myopathy of voluntary muscles, and exercise-related lactic acidosis. The patients had bilateral and total cataract in the first weeks of life, underwent cataract surgery, and developed nystagmus and strabismus. Corrected visual acuity was lower than 20/40 in aphakic eyes. Patients were mentally normal, and at school age they visited a school for blind and visually impaired children. The majority of the patients developed axial myopia with myopic fundus changes; aphakic refraction usually was lower than 10.0 diopters after the first decade. The cardiac myopathy was progressive and the cause of premature death. Three of the 12 patients died in the neonatal period and six patients died in early adulthood.

Descemet's Membrane Ruptures-Reply

In Reply. —The comments of Dr Quigley are interesting and worthy of consideration. Congenital glaucoma may be excluded in our group of patients for various reasons. As mentioned in our article, the corneal breaks were vertical and not horizontal or concentric with the limbus in the periphery (inconsistent with glaucoma). Also described in our article were the myopic retinal changes in the histories of cases 1 through 4. Not included in our article were the specific findings that the disc changes were those of a myopic configuration, rather than a glaucomatous excavation, and the corneal diameters were normal in all our patients. The IOPs for five of our seven patients have been recorded between 14 and 19 mm Hg. In no case was the IOP greater in the involved eye than in the fellow eye. The IOPs were unavailable for two patients, and these patients are unavailable for follow-up. We

Axial Length Changes after Retinal Detachment Surgery

A-scan echography was an accurate method for detecting changes in the depth of the anterior chamber, lens thickness, and length of the vitreous cavity after retinal detachment surgery in 30 eyes. Approximately 60% of the eyes had significant alterations in axial lengths exceeding+/-0.36 mm in aphakic eyes and +/-0.54 mm in phakic eyes. However, the operation of scleral bucklingg with large segments of hard silicone rubber implants or explants supported by an encircling band failed to result in a significant predictable shift of axial change in phakic or aphakic eyes. A-scan echography showed significant shallowing of the anterior chamber, and scleral buckling significantly increases lens thickness for at least six weeks. This induced a minor myopic refractive change that may explain some of the difference in postoperative refracitons between phakic and aphakic eyes.

Spectacle blur refraction of long time contact lens wearers.

Eighty-nine myopic patients, fitted with contact lenses, were studied for myopic change after 34.5 months of contact lens wear. The spectacle blur refraction, compared to the pre-fitting spectacle Rx was within ± 0.37 D for 76.3% of the patients without visual acuity loss. The contact lens in situ refractions, original and last, yielded similar data.