Year : 1983 | Volume
: 31 | Issue : 7 | Page : 823--826
Ultrasonic measurements of ocular components in angle closure glaucoma
LM Bhatia, A Panda, NN Sood
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi-110029
|How to cite this article:|
Bhatia L M, Panda A, Sood N N. Ultrasonic measurements of ocular components in angle closure glaucoma.Indian J Ophthalmol 1983;31:823-826
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Bhatia L M, Panda A, Sood N N. Ultrasonic measurements of ocular components in angle closure glaucoma. Indian J Ophthalmol [serial online] 1983 [cited 2021 Sep 20 ];31:823-826
Available from: https://www.ijo.in/text.asp?1983/31/7/823/29676
Angle closure glaucoma in its acute phase presents as an emergency and poses no problems whatsoever in its diagnosis. However, this may not hold true when one is confronted with such an eye in a state of normal tension. Certain anatomical as well as physiological factors are known to predispose an eye to angle closure attacks. Thus comparatively short eyeballs with shallow anterior chambers are common associated features of an eye; liable to develop an angle closure attack
This attack tends to occur at a younger age in our country. The present study was undertaken to look for an explantion if any, for the predisposition at an early age so as to establish comparative anatomical parameters in Indian population which has not been done so far.
MATERIALS AND METHODS
Eighty eyes of 40 cases of angle closure glaucoma were studied. Complete history of glaucoma was recorded. Refractive error was ascertained. A-scan ultrasonography using Kretz technik machine (7200 MA Austrian Model) was used to assess anterior chamber depth, lens thickness and total exial length of the eye ball. [Figure 1][Figure 2][Figure 3][Figure 4]. Controls having very close proximity as far as the parameter of re fraction; age and sex were considered. All subjects with family history of glaucoma were excluded.
Immersion technique was used for various biometric parameters. As velocity of ulaqueous and vitreous, so the calculations obtained from the lens also differ from those of aqueous and vitreous. Each microsecond in the lens is equivalent to 0.82 mm where as it is 0.76 mm in aqueous and vitreous, While calculating the total axial length, lens thickness, anterior chamber depth and vitreous chamber length were recorded separately and then the measurements were added to get the total length of the eye ball.
OBSERVATIONS AND DISCUSSION
The age distribution of the patients is highlighted in [Table 1]. Large majority of patients were seen in 41-50 years of age group and second largest in 51-60 years of age.
Similarly out of 40 index patients, 27 were found to be females and 13 were males, showing a definite preponderance of the females.
The mean anterior chamber depth of the cases were measured and compared with that of control groups [Table 2]. This was found to be significantly shallower in angle closure patients.
The lens was found to be thicker in cases of angle closure glaucoma as compared to the controls [Table 3].
The relative lens position was calculated by the formula:5
Anterior chamber depth + 1/2 thickness of the lens
Anteroposterior length of the eye ball and was found to be more anteriorly placed when compared to the controls [Table 4]. It is one of the impostant factors in producing shallow anterior chamber.
The axial length of the eye ball was measured and found to be less in cases of the angle closure glaucoma as compared to the controls [Table 5].
Various studies have been carried out to assess chamber depths in angle closure glaucoma cases. Tornquist8 reported an average of 1.59 mm of anterior chamber depth amongst swedes patients as compared to 2.6 mm in normal controls.
Auriceluo showed in Italians an average of 1.82 mm of anterior chamber depth in angle closure glaucoma as compared to 3.09 mm in normal controls.
In Japanese Aizewa demonstrated an anterior chamber depth of 2.33 mm as against 3.22 mm amongst controls.
Lowe reported that anterior chamber is 1.0 mm shallower in angle closure glaucoma as compared to the control.
Rosengran, Aizawa and Lowe also reported shallower anterior chamber in angle closure patients in different races of the world.
European studies by Lowe et al fouynd the highest incidence was amongst the age group of 61 to 70 years. However, studies by Awasthi et al, as well as the present study revealed the highest incidence between 41-50 years of age: Again there was.higher incidence of angle closure glaucoma as per our records of glaucoma. Present study was aimed to delineate certain critical biometric parametrs if any which would explain the earlier onset as well as higher incidence of angle closure attacks.
Alsbirk showed high incidence of 3.9% of angle closure glaucoma amongst Greenland Eskimos. The difference of anterior chamber depths between normal and the galucoma patients was 0.52 mm. In Europeans with far less incidence of angle closure glaucoma that means 0.09%, revealed a difference 1 mm or more of the anterior chamber depth.
The difference of anterior chamber depth in the present study was found to be 0.8 mm. This agains is quite less and compares well with Eskmios figures. This narrow difference of anterior chamber depth between normal and angle closure patients appear to be at the seat of higher incidence of angle closure attacks in Indian population. Thus it appears that besides shallower anterior chambers seen in younger age group, the narrow difference in the anterior chamber depth that means 0.8 mm is indeed a critical factor in causing higher incidence of attacks in same.
In 80 eyes of 40 cases of angle closure glaucoma the ocular biometry were measured by a scan ultrasonography. The cases were compared with 40 normal subjects of same sex, almost same age and refractive error. The eyes of the cases of angle closure glaucoma were found to have significant differences as compared to the control group as far as the axial langth of the globe and anterior chamber depth were concerned. This study not only revealed an increased lens thickness but also showed a significantly anteriorly placed lens as compared to the controls and thus is an important contributing factor in producing challower chamber in Indian population which predisposes the development of glaucoma.
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