Year : 1983 | Volume
: 31 | Issue : 7 | Page : 895--897
Quantitative assessment of conventional macular function tests in cases of cataract
AK Dubey, PH Masani, AP Shroff
Rotary Eye Institute, Navsari, Gujarat, India
A K Dubey
Rotary Eye Institute, Navsari, Gujarat
|How to cite this article:|
Dubey A K, Masani P H, Shroff A P. Quantitative assessment of conventional macular function tests in cases of cataract.Indian J Ophthalmol 1983;31:895-897
|How to cite this URL:|
Dubey A K, Masani P H, Shroff A P. Quantitative assessment of conventional macular function tests in cases of cataract. Indian J Ophthalmol [serial online] 1983 [cited 2022 Nov 29 ];31:895-897
Available from: https://www.ijo.in/text.asp?1983/31/7/895/29698
Rodenstock retinometer provides information about "Resolving Power" of the retina, independent of opacities of media and refractive errors. It give quantitative information about retinal function i.e. 6/12, 6/18 etc.
Maddox rod and two point discrimination have been conventionally used to assess the quality of macular function, whether "good" or "bad", particularly in cases of cataract before operation. Object of our study was to evolve a quantitative value of the conventional tests and to subject both the two tests and retinometer to critical evaluation.
MATERIAL AND METHODS
100 cases of cataract with no preoperative, post operative and intra operative problems were chosen as subjects. Pupils were fully dilated and tests performed as below:
(A) Retinometer readings were taken under full illumination of retinometer light, by projecting the interference fringes through the most transparent part of the cataractous lens (as patients did not answer readily if projection was made through dense lens opacity).
(B) Patients were made to sit 6 metres away from a bright electric bulb and maddox rod was placed infront of the eye to be examined, other eye being occluded, Maddox rod was rotated in three meridians, vertical, horizontal and oblique; and patients were asked about seeing a line, its colour, continuity, direction and straightness. Answers were graded as below:
Grade 1. Correct direction
(in all three positions) Continuity Straightness Correct colour
Grade 2. Correct direction
(in all three positions) Straightness but broken line Correct colour.
Grade 3. Only correct direction and colour
(Not definite about straightness
Grade 4. Can not interpret anything correc
tly but for colour.
(C) Two point discrimination test was done by putting a card board with two pin holes in front of the eye to be tested and answers were taken as "yes" or "no", wether the patient sees two points of light or not.
Patients were subjected to surgery and only cases where surgery was uneventful, and subsequent post operative period eventless, were included, for the study. any cases developing any such problems which will interfere with final visual acuity were excluded.
Cases were keenly examined on each post operative visit. 6 weeks after surgery best visual acuity with glasses was recorded. A comparison was made to evaluate the data provided by each of the three tests prior to operation.
All patients answered to maddox rod test readily and answers were clear and consistent, whichever be the grade.
Only some patients answered to two points discrimination test readily and correctly. Majority took time to answer and answers were incorrect and varying.
Of those patients who answered to retinometer reading, majority could not detect the oblique direction of interference fringes. Comparative table is given below:
a) Out of 100 cases operated 80 got a visual acuity of 6/6 to 6/9. All these cases gave a grade I response to maddox rod test preoperatively. Only 18 cases showed a corresonding retinometer reading of 6/6 to 6/9, 12 showed a reading of 6/12 to 6/18, 2 cases showed a reading of 6/24 to 6/36 while 48 cases showed a reading of 6/60 or less. Only 8 cases answered positively to two point discrimination test, rest 72 cases gave variable answers.
b) 4 cases had a vision of 6/12 to 6/18 and showed a consistent grade II response to maddox rod test, only one case gave a corresponding retinometer reading, while 3 cases gave a reading of 6/60. No case responded properly to two point discrimination test.
c) 6 cases regained a visual acuity of 6/24 to 6/ 36, out of these 5 cases had shown a maddox rod response grade III, and one had shown a grade I response. All 6 cases gave a retinometer reading of 6/60 or less. No case had shown a positive response to two point discrimination test.
d) 10 cases regained a visual acuity of 6/60 or less, all had shown a grade IV response to maddox rod. Only red light was recognised on retinometer, and no proper answers were given on two point discrimination test.
(1) Maddox rod test was found to be most acceptable to the patients, answers besides being quick, were consistent.
(2) A grade I response to maddox rod, denotes a vision of 6/6 to 6/9. Grade II, III, IV could not be given any definite value as number of cases in these groups was less, to form any conclusion.
(3) Retinometer was not readily answered to by the patients, and there were found large discrepencies in pre operative indicated visual acuity and final achieved post operative visual actuity. Retinometer readings were generally less then the final visual acuity obtained more so in cases where lens opacity was dense.
Oblique pattern of fringes was not recognised by majority of patients and a sizable no. of patients needed positive clue to recognise what they were seeing.
(4) Two point discrimination test was not received well by the patients, answers were incorrect or varying.
SUMMAY AND CONCLUSIONS
(1) A study on hundred cases of cataract was done to evaluate maddox rod test, two point discrimination test and rodenstock retinometer.
(2) Maddox rod test was found to be the most acceptable to the patients and reliable.A grade I correct response to maddox rod test indicated a visual acuity of 6/6 to 6/9.
(3) Retinometer was not found to be so useful in cases of cataract; and two point discrimination test did not give any useful results.
(4) Cost wise result wise, a maddox rod seems to be far more useful in cases of cataract, where largely a decision between "good" and "bad" vision is to be made and a grade I response can safely be taken to indicate a visual acuity of 6/6 to 6/9.