Relation of Refractive Error With Corneal Curvature of the Eye in Adult Subjects With Refractive Error

Abstract

BACKGROUND:The second most common reason for blindness worldwide is refractive error. Not only is the global burden of refractive error very high, but also increasing every day. A number of associated serious complications and the various modes of treatment aspect of the refractive errors, warrants the necessity to explore the various factors that have impact on them. The present study was done with the purpose of establishing the relation of refractive error with corneal curvature of the eye in adult subjects. This study was done on one thousand eyes, of five hundred adult cases, over a total period of 2 years. The cases included were of both sex's male and female, taken from Patiala and around Patiala. The subjects were recruited on the basis of inclusion criteria: refractive error-myopia and hyperopia, aged between 20-40 years. The subjects in our study included students of M.B.B.S. (Bachelor of Medicine and Bachelor of Surgery) and B.D.S. (Bachelor of Dental Sciences) and routine OPD (outpatient door) patients falling in the range of concern of my study. The instruments used in this study were: Auto refractor and Auto keratometer for measuring refractive error and corneal curvature respectively. Each subject was explained thoroughly about the whole procedure. Their informed written consent was also taken. General examination was done in each and every case. Thereafter local examination was done and the two concerned ocular parameters were recorded. The aim was to find in the subjects the type and degree of refractive error and corneal curvature and to find the relationship in between the two parameters. Statistical analysis was done of the data obtained. The results of our present study have showed that the spherical refractive error has statistically highly significant positive correlation with corneal curvature, in right eye (r=0.159, p<0.01) and in left eye (r=0.184, p<0.01). It means that as we progress from myopic to hyperopic refractive error accordingly the corneal curvature increases. In myopia or shortsightedness, image is formed in front of retina. Increase in myopic refractive error is found to be in close association with decreased corneal curvature. In hyperopia or long sightedness, image is formed behind the retina. Increased corneal curvature of the eyeball is found to be closely associated with hyperopia.

Correlation Between Myopic Refractive Error, Corneal Power and Central Corneal Thickness in the Egyptian Population

“…14 Arora et al, in 2015, studied 1000 eyes of 500 candidates with different types of refractive errors. 15 The mean age of our study subjects was 28.1± 5.79 years, with a range from 18 to 40 years. In contrast, the study by AlMahmoud et al included patients with a mean age of 40±10 years, ranging from 19 to 84.…”

“…12,13 The correlation between refractive error and corneal parameters has been previously studied in different regions and populations. 3,[14][15][16] The purpose of this work is to find out if there is any correlation between corneal parameters (namely, central corneal thickness and corneal power) and the refractive error in the myopic adult Egyptian population.…”

Corneal curvature in young high myopic undergraduates in southern Nigeria

“…1 Although, this study did not find any correlation between spherical equivalent and corneal curvature, some studies revealed that the spherical refractive error has statistically highly significant positive correlation with corneal curvature but other studies reached a similar conclusion that no significant correlation was present between spherical refractive error and corneal curvature. 6,10,[15][16][17] Several reasons may account for these differences in results from different studies, such as differences in age groups, refractive error ranges, sample size, populations, ethnicities, statistical power of the studies and various methods of measurement of various ocular parameters. 6…”

“…5 The prevalence of refractive errors especially myopia is currently attracting worldwide attention as many recent studies report dramatic increases over the last 20 years. 6 Anterior corneal curvature expressed in radii (mm) is important for contact lens fitting and management, ocular aberration analysis, corneal refractive surgery as well as diagnoses and management of corneal pathological conditions. 6 A cornea that is too curved (radii are abnormally small) is found in keratoconus and a cornea that is too flat is found in conditions such as cornea plana, which is a rare bilateral condition associated with severe refractive errors, cataracts and coloboma.…”

“…6 Anterior corneal curvature expressed in radii (mm) is important for contact lens fitting and management, ocular aberration analysis, corneal refractive surgery as well as diagnoses and management of corneal pathological conditions. 6 A cornea that is too curved (radii are abnormally small) is found in keratoconus and a cornea that is too flat is found in conditions such as cornea plana, which is a rare bilateral condition associated with severe refractive errors, cataracts and coloboma. 7 The measurement of the corneal curvature can be done by various instruments, such as a keratometer, keratoscope, IOL Master, or corneal topographer.…”