|Year : 1982 | Volume
| Issue : 6 | Page : 521-522
Soft lens spoilation
VK Dada, SC Acharjee
Dr. Rajendra Prasad Centre, for Ophthalmic Sciences A.LI.M-S., New Delhi, India
V K Dada
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, A T.T.M.S. New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dada V K, Acharjee S C. Soft lens spoilation. Indian J Ophthalmol 1982;30:521-2
Use of hydrophillic Contact lenses are in the increase for its comfort and prolonged wear. Deposits in the lens is one of the commonest cause of it being spoiled, leading to discontinuance of its use. This study was undertaken to study the nature of the deposits in 70% Sauflon lathe cut lenses manufactured in India from imported blanks.
| Materials and methods|| |
170 lenses fitted in the last one year for optical purposes. 50 lenses with suspected deposit were further screened with detailed biomicroscopy, dissecting microscopy, and microbiological study.
| Observations and discussion|| |
I. Calcium deposits :- It was observed that 5.29% of lenses calcium deposit in carbonate or phosphate form. Calcium carbonate deposits appears as needle like white crystals under magnification. They impart a sand paper feel to the contact lens and when extensive they may show protein. Boiling dissolves calcium carbonate. They can be seen as early as 3 days. Removal damages the lens permanently. Calcium phosphate deposits are milky white in nature with discrete bounderies.
Machanism of calcium deposition is not known. However certain factors like facilitate its deposition. (tear composition, poor blinking, atmosphere, poor tear production and protein deposits.) Another factor is hydrolysis of pyrophosphate (physiologic inhibitor of calcification) into phosphates. This is brought about by enzyme liberated by the injured tissue. Prevention by mechanical means and as far as possible control of environmental factor is the only remeady. Once it develops lens is irreversibly damaged. Except for direct relation with duration of wear there is no corelation with pH and wearing schedule.
II. Mulberry Spots : This was observed in 9.52% of our lenses. Basically it is composed of calcium phosphate which is often seen in combination with protein and lipoid. They appear like other deposits within the substance of the lens. Certain lens wearer are susceptible to form this. Replacement of lens gives temporary relief.
III. RUST Spots :- The incidence of iron spot was 4.11%. They gain access to the front surface from the poluted environment. Removal results in damaged lens surface. Other foreign materials like dust particles, consinetics were also found sticking on the lens surface during routine check up.
IV. Fungus Invasion :- Usually they appear as pinhead size with spots on the lens substance which do not disappear by usual method of cleaning. This spot gradually become larger and turns to blackish brown in colour. The sline is turbid and fungi can be demonstrated by direct examination under microscope. The lens itself can be put under a dissecting microscope which shows the characteristic mycelia. Cryo-section showed fungi invading the lens matrix on PAS staining.
Patient comes with irritation, redness and watering immediately after insertion of the lens, Vision is not usually effected unless the deposit is in the pupillary area. Some patient may remain asymptomatic. We have demonstrated Aspergillus fumigatus, Syncephalostrum, Alternaria along with involment by bacteria Pseudemonous aeruginosa in 8.82% of the spoiled lenses. On direct questioning of the patients we found that either they are not sterilising the lens properly as has keen instructed to them or they kept the lens unattended in the storing case for few days to few weeks.
V. Protein deposit :- It appears as a film on the surface of the lens. Incidence is more with a low pH of the tear. To avoid it lenses should be cleaned propery before thermal method of asepticization. By enzyme cleaning it can be removed. Source of such deposit have been attributed to lysozyme and various tear protein. We found 5.29% lens with protein deposit. Some lenses were found to have calcium deposit also in-addition.
VI. Brownish discoloration :- This was observed in 6.47% of lenses. Incidence is more when boiling is used as a method of asepticization. In our series, we have seen it as early as two months after lens wear. With the use of oxidizing agents in the laboratory the colour may become lighter to some extent. Bleaching agents remove the stain completely but cause much harm to the lens polymer, so much so that the lens becomes translucent and loses its suppleness. One of our lenses was discoloured yellow due to accidental use of sodium fluorescein.
VII. Other causes of Spoilation :-Damage of the lens may occur due to abrasions, broken edge, tearing of the lens and striation like finger prints. These occurs due to natural wear & tear after regular use, or due to faulty insertion, removal, storage and maintenance technique. Striation of lens surface is said to be developing in lenses sterilized by boiling. In one case in this series striations were noted where chemical method was used for sterilisation.
| Summary conclusion|| |
Out of the 170 Sauflon 70% lens fitted during the last one year 50 lenses were found to be spoiled due to various reasons. Detail study showed that inorganic, organic and mixed deposits are a source of serious demage to the soft contact lenses. Besides this damage due to normal wear & tear also cause spoilastion. All these causes intolerance of the lens leading to discontinuation and replacement which effects the patient as well as the practioner. Every endeavour should be made to prevent it because the damage to the lens is irriversable.