|Year : 1981 | Volume
| Issue : 3 | Page : 209-213
Refractive-status before and after contact lens wear
Dr. R.P. Centre for Ophthalmic Sciences, A.I.I.M.S., New Delhi, India
V K Dada
Dr. R.P. Centre for Ophthalmic Sciences, A.I.I.M.S., New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dada V K. Refractive-status before and after contact lens wear. Indian J Ophthalmol 1981;29:209-13
Changes in refractive status with contact lens wear have been highlighted from time to time in the literature.
This study was undertaken at Dr. Rajendra Prasad Centre for Ophthalmic Sciences to evaluate the effect of contact lens on the behaviour of myopia in subjects of growing age.
| Methods and materials|| |
130 eyes of sixty subjects in the age group of 12 to 20 years were studied. Keratometry and refraction was done (1) Before fitting the contact tense, (II) After three years of regular contact lens wear and (III) after 3 weeks of total lens withdrawn.
| Observation and discussion|| |
This study compares the changes in cylinder and spherical refraction at three stages. 3 weeks interval between 2 and 3 ensure estable refractive and Keratometry stages. Comparison of stage I and III highlights the final change in cylinder and sphere. In comparison of stage II and III was done to guide the fitter about prescription of glasses in contact lens wearer. Comparison of stage I and II was highlighted to seethe effect of 3 years wear after immediate lens removed. [Table - 1], II and III compares cylindrical changes between stage I and II, I and III, II and III respectively. [Table - 4][Table - 5][Table - 6] similarly compares the spectacle changes between Stage I and II, I and III, and II and III.
[Table - 7], represents the comprehensive commulative percentages of all the above six stages.
[Table - 8], corelates the Keratometric and the spectacle changes.
For statistical comparison a differential mean has been projected in the table instead of the range. It is clear from the comprehensive cummulative percentage [Table - 7] that in the first stage of comparison between group I and II cylinder increase and decrease was noted in 52% and 32% respectively. Cylinder remain the same in 16% in stage II which compare I and III increase and decrease was noted in 55.73% and 37.63% respectively original unchanged cylinder was noted in 6.6% stage III compared status II with III and highlighted that 70% showed a change in cylinder, that is increase in 44% and decrease in 26%. No change was seen with lens withdrawn in 30%.
Similarly [Table - 7] compare the spectacle results after contact lens, comparison of status I and III indicates that spectacles refraction decrease in almost 76% an increased was noticed in 17.5% and status quo was noticed in 6.5%. Result of three weeks rest are indicated in comparison of status II and III and it is clear that change was noted in 80% and refraction remain the same in 20%. Refractive status increased in 50% and decreased in 30%. Further from [Table - 8] it is clear that Keratome and the Spectacle changes were corelated, only in 10.28%. In the remaining 89.72% Keratom.etry changes were greater, lesser or opposite to spectacle changes in 41.12%, 28.97, and 19.62% respectively.
It is clear that 76% showed a decreased in Myopia which has gone to an extent of 2.25 D, in somehow it has been achieved with contact lens seems to be due to its effect on the accommodational status.
| Summary|| |
However, following highpothesis can be forwarded has to how contact lens retards Myopic progression.
(I) Contact Lens Results/in larger retinal image.
(II) Contact Lens a larger field.
(III) Contact Lens of full power-MYOSIS, Better depth of focus.
(IV) Contact Lens causes natural shift towards accommodation convergence relationship.
(V) Contact Lens has retaining effect on Curvature.
(VI) Contact lens has pushing back effect on stretching of eye ball coats.
(VII) Contact Lens given flat less minus.
(VIII) Contact Lens exert gentle effect metabolism and curvature (HYPOXIA).
This study has also highlighted the concept that 3 weeks rest is essential before refractive
status is evaluated.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7], [Table - 8]