|Year : 1983 | Volume
| Issue : 7 | Page : 928-930
Fitting and analysis of soft contact lens
LD Sota, Ajay Deora
Guru Nanak Eye Centre: Maulana Azad Medical College, New Delhi, India
L D Sota
Guru Nanak Eye Centre: Maulana Azad Medical College, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sota L D, Deora A. Fitting and analysis of soft contact lens. Indian J Ophthalmol 1983;31, Suppl S1:928-30
Early in the year 1960 Soft Contact Lenses were manufactured form hydroxyethyl methacrylate in Czechoslovakia. These lenses had many- problems like breakability, poor oxygen permeation, corneal staining, oedema etc. But at the sametime it had the advantage of easy fitting and adaptability. So came many improvements and many new materials came into existence. In this study sauflan and vizi lens of 70% and 55% were used. Material was purchased from Contact Lens Lab London, U.K. and George Nissel London and the lenses were manufactured in our own lab at Guru Nanak Eye Centre.
| Material and methods|| |
Four hundred eyes were fitted with soft lens. All patients were myopic upto the range of -8 D with a maximum astigmatism of upto-1.50 D. Hypermetropes and aphakic patients were not considered in this study.
| Fitting procedure|| |
Routine examination like refraction, slit lamp examination, keratometry, ophthalmoscopy and measurement of the visible iris diameter was taken. First lens was fitted 0.40 to 0.60 mm flatter than the flattest `K' reading and diameter of the lens was 1.25 mm to 1.50 mm larger than visible iris diameter. Let the lens settle down for 15-20 minutes. Observe the movement of the lens. There should be small amount of movement and no displace-t ment of the lens and lens must reposition itself on decentring. Lens should not produce any indentation on the sclera and no blanching of the conjunctival vessels. Vision should be clear during and in between the blinks. Keratometery should be done with the lens in situ. Mires should be clear and not distorted or variable, double or out of shape. The position of the lens on the extreme position of the eye should not show much variable. Careful slit lamp examination should be done.
Only those patients who were able to wear lenses 8-10 hours a day were taken into study and the follow up was done at 6-months and 1 year, 2 years, 3 years and 4-years or as and when necessary. Replacement of the lens was done as and when required.
Follow up was divided into two parts:
1. Changes in the Eye.
2. Changes in the Lens.
| Observation|| |
Following changes were studied. Changes in Visual acuity
The follow up was one and half year. At the end of one year 70% of the patients had decrease in visual acuity upto maximum of one line. In the rest of 30% of the patients they alsc described their vision was of slightly pool quality now than what it was at the time of geting the lenses. No significant change wa,, observed earlier. No correlation could be observed in change of visual acutiy with the degree of myopia or astigmatism. Seventy percent of patients required change of lenses after 1'/2 years.
Changes in Corneal Curvature
The follow up was for two years. Change,, in the corneal curvature were noted at the enc of one year and two years. 150 eyes were studied. No significant change in corneal curvature was noted in the first one year. At the end of 2nd year, 70 to 75% showed no change And flattening and steepening of corneal cur. vature was almost equal. [Figure - 1].
Changes in the Refractive Error
Follow up was for 1'h years. As most of the patients had to purchase a new pair of lenses. Refractive error was estimated immediately after removing the lens, Change of ±0.50 D was considered as insignificant. In 50% of the patients an increase of 0.75 to 1.25 D was observed. In 10% decrease of the same amount was observed and in 40% no change was observed. [Figure - 2]. So it is concluded that soft lense have no effect on the refractive error. This increase could be seen otherwise also.
This is the greatest danger to the soft lens wear. This was seen if the lens was worn daily for three years. It started all round the cornea. Start was seen mostly in the upper quadrant and was more pronounced probably because of the same reason as for the trachoma. This extends if not checked by discontinuation of the lens. To begin with it is very small and superficial. In 15% of cases it started after three years ofwear and at the end of4 years the percentage increased to 18%. To our mind this is a greatest danger in the best fit soft lens in long run. It may soon be responsible for the unpopularity of the soft lens in the near future and may remain good only for special wear for sportsmen and occasional wearers.
changes in the Lens
Discolouration of the lens was a common phenomenon. It started usually from 6months onward. It was more in 70% than 50% water content lens. Complete naked eye visible discolouration and deposit in the lens was seen after 1 12 years to 2 years. Change of lens colour was definitely seen in over 95% of cases after 2 years. Touching of the soft lens with cosmetic colours or kajal resulted in immediate discolouration and required a change. Breaking of the lens or chipped lens was seen in 30% of cases and was due to mishandling. Spontaneous breakage was seen only in 2% of cases.
High rate of infection as reported previously was almost not seen now due to proper precautions taken. Infection is not a hazard if proper hygeine is observed and instruction given to the patients such as proper cleaning, handling, discontinuation of the lens if redness appears and frequent visits to Ophthalmologist.
[Figure - 1], [Figure - 2]