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PubMed1975

Influence of the myopia gene on brain development.

Evaluation of the performance of 17-18-year-old high school students on standard intelligence tests confirms previous reports that nearsighted persons consistently achieve scores approximately eight I.O. points higher than non-myopes. Comparison of tests administered to the same students 10 years earlier suggests that the intellectual gain precedes the development of nearsightedness. Since there is convincing evidence from genetic studies that myopia is an inherited condition, probably transmitted as a recessive characteristic, it is concluded that the myopia gene has a stimulant action on the brain in addition to its effect on the eye. The high frequency of myopia in urbanized societies is explained in terms of an evolutionary adjustment, myopes probably having a survival advantage under conditions of industrialization.

Adolescent↗
PubMed2005

Aberrations and myopia.

It has been suggested that high levels of axial aberration or specific patterns of peripheral refraction could play a role in myopia development. Possible mechanisms involving high levels of retinal image blur caused by axial aberrations include form deprivation through poor retinal image quality in distance vision, enhanced accommodative lags favouring compensatory eye growth, and an absence of adequate directional cues to guide emmetropization. In addition, in initially emmetropic eyes, hyperopia in the retinal periphery may result in local compensatory eye growth, which induces axial myopia. Evidence in support of these ideas is reviewed and it is concluded that, for any fixed pupil diameter, evidence for higher levels of axial aberration in myopes in comparison with other refractive groups is weak, making involvement of axial aberrations in myopization through image degradation at the fovea unlikely. If, however, some potential myopes had unusually large pupil diameters, their effective aberration levels and associated retinal blur would be larger than those of the rest of the population. There is stronger evidence in favour of differences in patterns of peripheral refraction in both potential and existing myopes, with myopes tending to show relative hyperopia in the periphery. These differences appear to be related to a more prolate eyeball shape. Longitudinal studies are required to confirm whether the retinal defocus associated with the peripheral hyperopia can cause patterns of eyeball growth which lead to axial myopia.

Accommodation, Ocular↗
PubMed1996

Trends regarding myopia in video terminal operators.

A longitudinal study with a 4-year follow-up was carried out on 6101 employees of the Italian Telecommunications Company (Telecom Italia) to study the role of work at Video Display Units (VDU) for the evolution of different types of myopia (mild, intermediate and pathologic). The refractive modifications of myopic VDU operators were further studied with regard to differences in time of use of VDU (daily hours and years spent working at a VDU). No statistically significant difference was found for refractive modifications, neither with regard to the type of myopia, nor to the daily hours and years spent working at a VDU. The results have indicated that the use of VDU is not responsible for a worsening of myopia.

Adult↗
PubMed1997

Myopia in children born premature or with low birth weight.

PURPOSE: To evaluate the association of myopia or astigmatism in children without retinopathy of prematurity (ROP) born premature or with low birth weight. METHODS: This cross-sectional study was conducted in Singapore where 527 children from three kindergartens aged 2 to 7 years without a history of ROP were recruited. Information on birth weight and gestational age at birth was obtained from a personal booklet and the refractive error in spherical equivalents was measured using distance photoretinoscopy. The data was analysed with univariate analysis and logistic regression models. RESULTS: There was no difference in the prevalence of myopia in children born premature or with low birth weight. There was also no difference in astigmatism in children born premature or with low birth weight. CONCLUSION: This study shows no relationship between astigmatism or myopia with prematurity or low birth weight in children born without retinopathy of prematurity.

Astigmatism↗
PubMed1997

Myopia among the Inuit population of East Greenland. Longitudinal Study 1950-1994.

PURPOSE: To follow the refraction values in an indigenous population group over the course of the past 50 years. METHOD: Case records from a population investigation carried out in Ammasalik, East Greeland, by Erik Skeller in 1950 were studied initially, a total of 1123 eyes were examined by sciascopy and 244 eyes could be followed sufficiently until about 1990-94. RESULT: The mean refraction was initially +0.08 D, while at the last examination the mean had increased to +0.69 D. Initially, there was no myopia, defined as at least -1.5 D, and at follow-up it was a maximum of 1%, and presumably due to immature cataract. A tendency to myopia (< -1.5 D) was found initially in 36%, but in only 22% at follow-up. CONCLUSION: The myopinizing factor in East Greenland has not affected persons born prior to 1942, even if they had a tendency to myopia (< -1.5 D).

Adolescent↗
PubMed2005

The effect of parental history of myopia on eye size of pre-school children: a pilot study.

PURPOSE: To evaluate parental history of myopia as a predictor of refractive error and eye size in Chinese pre-school children. METHODS: A total of 514 pre-school children (aged 2.3--6.4 years) were examined. Parental history of myopia, amount of near work performed, refractive status and ocular biometry were recorded. RESULTS: There was no significant difference in spherical equivalent refraction (SER) among children with no myopic parents (mean+0.94+/-0.05 D), one myopic parent (mean+0.77+- 0.07 D) and two myopic parents (mean+0.79+/- 0.12 D) (p=0.102) after controlling for age and amount of near work. Further, children with more myopic parents did not have longer eyeballs (p=0.335). CONCLUSIONS: In this study in Chinese pre-school children, parental history of myopia was not found to be associated with a myopic refractive error or increased eyeball length. Further studies with larger sample sizes would help to confirm these results.

Asian People↗
PubMed2005

Central corneal thickness in high myopia.

PURPOSE: To examine if central corneal thickness (CCT) is different in emmetropia and high myopia. METHODS: 57 emmetropic subjects (0 to + 1.5 D) and 48 high myopes (all more than - 6 D in spherical equivalent refraction) were studied. CCT was measured by a Haag-Streit Optical Low-Coherence Reflectometry (OLCR) pachymeter, a recently developed high precision pachymeter with a standard deviation (SD) for repeated measurements of 1 microm. RESULTS: Mean CCT for the emmetropic group was 538.6 microm (SD = 32.1), and for the myopic group 527.7 microm (SD = 35.0). Neither the mean CCT nor the variance from the two groups showed a statistically significant different (p > 0.05). CONCLUSION: CCT is not systematically altered in myopia. The process by which the myopia progresses does not to a measurable degree influence the central cornea.

Adolescent↗
PubMed1985

Prevalence of myopia in school children in Vanuatu.

The onset of myopia typically occurs in childhood and increases during puberty. We studied the vision and refractive errors of 977 school children (ages 6 to 17 years) in 1983. Myopia in the group was extremely low; 97% had vision of 6/6, and 1.3% had myopia greater than 0.25D. Regression analysis revealed a change in mean refraction of -0.016D/year for males and -0.024D/year for females. There were no significant differences between males and females. These children engaged in about 8 hours of school work per day, and we conclude that genetic factors predominate over environmental factors in the determination of myopic refractive errors for this group.

Adolescent↗
PubMed1988

The role of environmental factors and hereditary predisposition in the causation of low myopia.

Various environmental factors have been implicated in the etiology of myopia. An attempt was made quantitatively to estimate some such environmental factors, as based on the presence or absence of a family history of myopia. Age range was 10-21 years. The 200 subjects included in the study were further divided according to emmetropia/myopia. The factors studied in the four subgroups were amount of near work done per day, head posture and illumination level while doing near work, acute fevers, chronic illness, acute or recurrent diarrhea, nutritional status, and income levels. A correlation was found between myopia and near work, head posture and income levels.

Adolescent↗
PubMed1989

Progressive cone-rod dystrophy and high myopia in a Finnish family.

Progressive cone-rod dystrophy was diagnosed in a 35-year-old man (the proband). In the family study, 29 of the relatives were examined. The brother of the proband was also found to have cone-rod dystrophy. In the family of the mother of the proband, there were four men who had high myopia possibly connected with cone-rod dystrophy. The other relatives had no signs of cone-rod dystrophy or high myopia. The relatives not examined were reported healthy with no eye trouble. The disorder could be autosomal recessive hereditary if only the confirmed cone-rod dystrophy of the proband and his brother is taken in consideration. However, no relationships between the families of the mother and father of the proband could be found going back to the year 1830. Therefore, the autosomal recessive inheritance was not established. The most probable mode of inheritance would be X-chromosomal recessive if high myopia and cone-rod dystrophy are thought to be parts of the same syndrome.

Adolescent↗
PubMed1990

Refraction in diabetics during metabolic dysregulation, acute or chronic. With special reference to the diabetic myopia concept.

The influence of diabetic dysregulation on refraction was analysed by a short-term and a long-term approach. a) Out of 15 patients admitted due to high blood sugars and followed over weeks, 11 showed refractive fluctuation of 1-6.5 D, in either direction-often with excess hypermetropia, while 4 appeared refractively stable. In those with refractive change a transient increase of lens thickness was suggested from ultrasound measurements. b) Diabetes control was evaluated retrospectively in 74 adult diabetics, mainly based on repeated 24 h urine glucose determinations over a 6-year period. As a group, those with low myopia did not score worse than those who had stayed emmetropic. Among the myopes, diabetes duration was longer in the subgroup where diabetes preceded myopia onset. - All considered, we found no support for dysregulation per se as an underlying factor behind the 'diabetic myopia' previously reported from our clinic.

Acute Disease↗
PubMed1990

Myopia and radial keratotomy: a survey among Norwegian ophthalmologists.

One hundred and eighty-nine of 200 ophthalmologists in Norway responded to a survey requesting them to report their age, sex, refractive state, use of corrective lenses, and if myopic, their view on radial keratotomy as a possible method to correct their own myopia. According to the answers, 32 (17%) females and 154 (82%) males, with mean age of 49 years, were registered. The reported refractive state was 26.5% emmetropy and 72.0% ametropy. The prevalence of myopia was 45%. The mean refractive status (equivalent sphere) in the right eye was -1.02 +/- 2.28 D with a range from -8.5 D to +7.25 D (n = 184). Of the ametropes, 64.8% used spectacles, 15.3% used both spectacles and contact lenses, whilst 3.6% used only contact lenses for distance vision. With the exception of one, all myopes used corrective lenses. Only 2 myopic ophthalmologists responded positively to the question of whether they would consider having radial keratotomy to correct their own myopia.

Adult↗
PubMed1993

Experimental myopia in a diurnal mammal (Sciurus carolinensis) with no accommodative ability.

1. We examined the functional morphology of the intra-ocular muscles of the grey squirrel using pharmacological and histological methods. Using sympathomimetic (phenylephrine) and parasympathomimetic (carbachol) agents, administered by transcorneal iontophoresis, the response of the iris sphincter and dilator muscles and the ciliary muscle were recorded. Measurement techniques included both streak retinoscopy and coincidence optometry for measurement of ocular refraction and high resolution ultrasonography to monitor changes in the intra-ocular component dimensions. 2. The grey squirrel was found not to possess a functional accommodative system. No change in ocular refraction or intra-ocular dimensions could be induced with 40% carbachol. Marked changes in pupil diameter occurred with topical application of both phenylephrine (dilation) and carbachol (constriction). Histological findings were in agreement with pharmacological findings in showing well developed iris sphincter and dilator muscles but only a poorly developed ciliary muscle. 3. Calculation of the depth of focus of the grey squirrel eye reveals that this could be sufficient to account for the behavioural observations of near viewing habits. 4. We then determined whether we could induce axial elongation of the vitreous chamber and a consequent myopia by monocular deprivation (MD) of pattern vision. 5. Monocular deprivation of pattern vision produced a significant experimental myopia due to axial elongation of the vitreous chamber in the deprived eye. 6. The results demonstrate that a functional accommodative system is not necessary to induce experimental myopia in the grey squirrel eye.

Accommodation, Ocular↗
PubMed2005

The preoperative intraocular pressure level predicts the amount of underestimated intraocular pressure after LASIK for myopia.

AIMS: To evaluate the statistical significance of the parameters that affect underestimation of intraocular pressure (IOP) after laser in situ keratomileusis (LASIK) for myopia. METHODS: In this prospective case series study, patient age, axial length, preoperative corneal curvature, preoperative central corneal thickness (CCT), preoperative IOP, and ablation depth were studied to determine whether they affect the underestimation of IOP in the right eyes of 100 consecutive patients who underwent LASIK. RESULTS: The preoperative IOP was the most important parameter for an amount of underestimated Goldmann applanation tonometric IOP (GAT) and non-contact tonometric IOP (ncIOP) at 1 month (r = 0.654, p<0.0001, R(2) = 0.427, and r = 0.694, p<0.0001, R(2) = 0.481, respectively) and 3 months (r = 0.637, p<0.0001, R(2) = 0.406, and r = 0.726, p<0.0001, R(2) = 0.527, respectively). Patient age was statistically significant for underestimating the GAT at 1 month, and both the ablation depth and CCT were statistically significant parameters for underestimating the ncIOP at 1 month and at 3 months by stepwise multiple regression analysis (F>4.000). However, these parameters had small bivariate correlation coefficients, and were considered as minor parameters. CONCLUSION: Preoperative IOP is the most important parameter that affects an underestimation of IOP after LASIK for myopia. Eyes with a higher true IOP have a larger underestimation of the IOP after LASIK for myopia. From these results, the importance of the modulus of elasticity on IOP measurements was discussed.

Adult↗
PubMed2006

Intravitreal bevacizumab (Avastin) as treatment for subfoveal choroidal neovascularisation secondary to pathological myopia.

OBJECTIVE: To evaluate the safety and efficacy of intravitreal bevacizumab (Avastin) as treatment for subfoveal choroidal neovascularisation (CNV) due to pathological myopia. METHODS: Consecutive series of primary or recurrent subfoveal CNV secondary to myopia treated with intravitreal bevacizumab 1.25 mg between August 2005 and January 2006 at the New England Eye Center, Boston, Massachusetts, USA, were reviewed retrospectively. Data from clinical examination, fundus photography, fluorescein angiography, optical coherence tomography and visual acuity were collected. RESULTS: There were 11 eyes of 9 patients. 5 of 11 eyes had been treated previously with photodynamic therapy. Pre-injection visual acuity measured 20/50 to 20/100 in 6 eyes and 20/200 or worse in 5 eyes. After a mean follow-up of 153 (range 35-224) days, post-injection visual acuity measured 20/20 to 20/40 in 7 eyes, 20/50 to 20/100 in 1 eye and 20/200 or worse in 3 eyes. Three eyes received two bevacizumab injections and eight eyes received one injection. Visual acuity improved by a mean of +3.5 (range -1 to +8 lines) lines, and 8 of 11 eyes achieved 20/50 or better at the last follow-up. Central foveal thickness improved from 340 (range 253-664) microm to 234 (range 142-308) microm, representing an average reduction of 103 (range +4 to -356) microm. No injection complications or drug-related side effects were observed. CONCLUSIONS: In this small series of eyes with limited follow-up, intravitreal bevacizumab seems to be safe and potentially efficacious in eyes with subfoveal CNV secondary to pathological myopia.

Adult↗
PubMed1983

Myopia in premature babies with and without retinopathy of prematurity.

One hundred and fifty-five premature infants weighing 600-2000 g were followed up during 1974-80 for the presence of retinopathy of prematurity (ROP) and for the existence of myopia. 50% of the premature infants who had ROP were myopic, while only 16% myopic premature infants were found among those who did not have ROP. There was a positive correlation between the degree of myopia and the severity of cicatricial ROP. No difference existed in the frequency and degree of myopia between premature infants in which ROP cicatrised spontaneously and in those where it cicatrised after cryopexy.

Birth Weight↗
PubMed1995

Excimer retreatment for scarring and regression after photorefractive keratectomy for myopia.

AIMS/BACKGROUND: Scarring associated with regression of refractive effect can occur after photorefractive keratectomy (PRK) for myopia. The experience of treating these complications is reported. METHODS: Eighteen of 285 eyes (6.3%) were retreated with the excimer laser. Age, sex, preoperative primary treatment keratometry, pre-primary treatment, pre-retreatment and post-retreatment spherical equivalents, best corrected and uncorrected visual acuities were recorded and analysed. RESULTS: At 6 months post-retreatment, the mean spherical equivalent was -2.07 dioptres (D) (SD 4.60 D). This spherical equivalent persisted in eyes followed for 12 months (-2.85D, SD 4.09 D). Nine of 18 eyes (50%) had uncorrected visual acuity of 6/12 (20/40) or better. If retreatment was undertaken within 6.5 months of the initial PRK, then scarring was likely to recur (p = 0.035). Nine of 10 eyes (90%) which had a retreatment spherical equivalent less than two thirds of their primary treatment spherical equivalent were within plus or minus 1.25D from emmetropia after retreatment. Four of 11 eyes (36%) followed for 12 months after retreatment rescarred with further regression. CONCLUSION: The data showed that eyes with scarring and regression of myopia should not be treated with PRK within 6 months of the initial procedure. Eyes with the highest percentage of regression towards their initial myopia tend to have a poor response to retreatment.

Adult↗
PubMed1996

Psychological aspects of excimer laser surgery for myopia: reasons for seeking treatment and patient satisfaction.

AIMS: To determine the reasons patients seek excimer laser treatment for myopia and to measure levels of patient satisfaction with each phase of this relatively new treatment. METHODS: A unique 38 item visual analogue questionnaire was developed and applied to 100 consecutive patients (n = 100) who had undergone excimer laser photorefractive keratectomy for myopia or myopic astigmatism at a single centre. All subjects underwent extensive ophthalmic assessment and patient education before treatment. RESULTS: A 90% response rate was achieved (n = 90). Improved unaided vision (85.6%), freedom from spectacles (83.3%), and difficulties with contact lens wear (72.7%) were the most common reasons for seeking treatment. The majority of patients felt that the quality of their life had improved (85.5%) and 82% felt that the quality of their unaided vision was as good as they had anticipated. overall, 95.5% of patients were pleased that they had undergone this procedure. The vast majority (98.9%) of patients felt that they fully understood the operation pretreatment but almost one quarter (23.9%) found the actual operation distressing. Only 15.7% found postoperative pain did not respond adequately to prescribed analgesia. CONCLUSIONS: This study demonstrates a very high level of patient satisfaction after excimer laser treatment for myopia and myopic astigmatism. It suggests that most patients seek treatment to enjoy better vision free from optical aids and that a high level of patient education preoperatively may establish realistic expectations and satisfaction with overall outcome.

Adult↗