|Year : 1986 | Volume
| Issue : 1 | Page : 1-5
Refractive error stress in the aetiology of senile cataract
SK Angra, KP Adhikari, VK Dada
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India
S K Angra
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi 110029
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Angra S K, Adhikari K P, Dada V K. Refractive error stress in the aetiology of senile cataract. Indian J Ophthalmol 1986;34:1-5
|How to cite this URL:|
Angra S K, Adhikari K P, Dada V K. Refractive error stress in the aetiology of senile cataract. Indian J Ophthalmol [serial online] 1986 [cited 2020 Feb 18];34:1-5. Available from: http://www.ijo.in/text.asp?1986/34/1/1/26352
The aetiology of senile cataract is controversial still and one of the theories put forward to explain the aetiology included stress of accommodation,,. The onset of the lenticular opacities in Indian subcontinent is early and so is presbyopia. Is there any relationship of the accommodational stress (Presbyopia) or refractive error with cataract formation? We endeavoured to probe into it.
| Materials and methods|| |
Patients between age of 30-40-45 years from 50 Km. around Delhi were randomly included in this study and were investigated for visual refractive status and presence of lenticular opacity under cycloplegia. The patients were grouped as under [Table - 1] uncorrected.
I. Hypermetropic patients with uncorrected presbyopia.
II. Uncorrected hypermetropia with corrected presbyopia.
III. Corrected myopia without correction of presbyopia.
IV. Presenile cataract.
A thorough examination of the crystalline lens was done with fully dilated pupil on slit lamp to detect early cataract (Cuneiform or any other type of cataract). Screening of the periphery of the lens was done with 3 mirror Goldmann Contact Lens for any lenticular opacity. The opacities were recorded topographically. Anterior chamber depth was measured by Pachometer using Haag-Streit 900 slit lamp. The Binocular as well as uniocular accommodation and convergence were measured.
The randomisation and masking was incorporated in this study. The records of refractive status, accommodation status and topography of lens were kept independently masked and were correlated at the end of the study. High hypermetropes and high myopes were excluded from the study.
| Obsfrvations|| |
There was no statistically significant difference between the degree of refractive errors, accommodation stress in patients with or without cataract in group I,II and III. [Table - 2],[Table - 3]. A.C. depth did not show any statistically significant variation in different groups.
The prevalence of type of lenticular opacity varied with type of refractive error [Table - 4].
In the earliest type of Cuneiform opacities, the opacity were observed mid-way between the capsule and the zone of disjunction in the anterior as well as posterior cortext. The subcapsular opacities were present in the posterior cortex in the axial region. The morphological characters were not of complicated type of cataract but of early Cupuliform variety.
There is no statistical difference between cataract and non-cataract patients as regards stress of near work in their profession.
In group IV, 30 cases of presenile cataract showed that the patients with Cuneiform type of cataract were found to be hypermetropes whereas patients with posterior subcapsular and nuclear cataracts were myopes. [Table - 5]. This agrees with our findings in group I, II and III.
| Discussion|| |
A functional theory that the strains of accommodation bad a deleterious effect on the lenticular fibres, leading to opacification was put forward by various workers. The macbanism of opacity formation was put forward differently by different workers. Fisher put forward that the time of onset of early cataract changes in the lens probably corresponds with the period of maximun accommodational stress, i.e. just after the onset of presbyopia. He did in-vitro experiments to test this hypothesia. Fisher further distincuished two maturation periods. coronal cataract having earlier than nuclear outs.
The Cuneiform opacities in our cases lie in mid cortex (between capsule and zone of disjunction between nucleus and cortex). This region is more prone t o shearing stress. The cortex gets sclerosed gradually, proportional to the proximity to the nuclear zone. The acommodational moulding stress does not affect the superficial fibres but exerts on the mid cortex [Figure - 1]. We feel that cuneiform opecities have not started under the capsule and are pushed down but these have developed in this very zone as has been noted at the same place in different people of different age with different degree of hypermetropia.
Thus we differ from Fisher, who believes that the cuneiform opacities start under the capsule and are pushed to mid cortex and as the presbyopic accommodational stress being short lived, the superficial fibres laid remain normal. In our study we could not attribute the relationship of cuneiform opacities to presbyopia as these are present in persons using presbyopic glasses and not using presbyopic glasses to the similar degree and extent. Secondly if we apply the concept by Fishers, the dating of opacification in lens falls back to the age group of 35-40 years which is not the age group of presbyopic accommodational stress. Thus our obeservations support Goldmane, who noted that lamellar separation is precursor of cuneiform opacities which occur in middle and deep layer of cortex.
In our study the occurrence rate of cuneiform opacities and accommodational reserves in hypermetropes, using glasses and not using glasses, for near and distance, is similar without any statistically significant difference. Wben we compare the prevalence of cataract in subgroups of each groupie. one group using more accommodation (for near and distance) in their day today life and another group using not more acccmmodation for near in their day to day life, there is no significant difference in the number of patients with cuneiform cataract. Thus we conclude that presbyopic accommodational stress has no role to play in causation of cataract i.e. cuneiform cataract. This is not in agreement with concept of Fisher that presbyopic accommodational stress might be the cause of cuneiform cataractous changes.
But when we compare hypermetropic groups (1&I1) with myopic group (Ill), the latter not using exessive accommodation for near or distant as they have good reserves of accommodation, the prevalence of cataract types is different. Interestingly, the prevalence of cuneiform cataract is almost negligible in myopic group (III). This indicates that there is some role of accommodation per se in the causation of such cuneiform lenticular opacities. We feel it is continuous accommodational stress to compensate facultative hypermetropia rather than presbyopic accom. m )dation it stress, which is responsible for occurrence of cuneiform opacities at mid cortex level. It m ty be that excessive physical accommodational moulding causes maximum shearing stress at mid cortex zone presumibly leading to disturbed physiological milleau. [Figure - 1],[Figure - 2] This area might become more prone to noxious environmental influences like U.V. light, nutrition, etc., which trieger the process of cataractogenesis to bring about morphological change.
We have also observed that the posterior subcapsular opacities are commonly found in myopic patients who do not use accommodation for distant vision and have comparatively enough reserves for near work. These are not related to accommodational stress. The possible relation between refractive error and disposition of cortical cataract is the prevalence of 'cuneiform cataract in hypermetropes and posterior subcapsulor lens opacities (Cupuliform) in myopes. This observation is further supported by our findiings from the study of morphology profile pattern of presenile cataract. We also support Duke Elder that post-subcapsular opacification in lens is most typical in myopes and feel that is to be precursor of cupuliform cataract.
Our cases belong to the age, much lower than those of prone to nuclear cataracts. Our observations do not contradict those of Weale that myopes (t : 100) are prone to nuclear cataracts in patients in early sixties than hypermetropes (I : 1000) as the age and type of cataract in our cases are different. More field trials of this hypothesis are needed 'and early correction of hypermetropes might be the preventive outcome of this study.
| Summary|| |
The early lenticular opacities (cuneiform cataract and posterior subcapsular) are related to refractive status found in a randomised masked study.
| References|| |
Duke Elder S., 1970, System of Ophthalmology, Vol. XI, Henry Kimpton, London.
Fisher R.F., 1970, Trans. Ophthalmol. Soc. U.K. XC : 93.
Fisher R.C., 1973, Human Lens-in relation to cataract. Ciba Symposium Foundation Amsterdom P 307.
Chatterjee A., Milton R.C. and Tyles S., 1982, Brit. J. Ophthalmol. 66: 35.
Angra S.K. & Mohan M, 1979, Ind. J. Ophthalmol. 27, III : 37.
Goldman H., 1937, Cited by Duke Elder, S.
Goldman H, m, 1964, Amer. J. Ophthalmol. 57 :1.
Weale R.A., 1980, Brit. J. Ophthalmol. 64:311.
[Figure - 1], [Figure - 2]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]