|Year : 1984 | Volume
| Issue : 6 | Page : 525-527
Light differential threshold studies of reattached retina and macula
DC Talsania, RN Mathur
M. and J. Instt. of Ophthalmology, Ahmedabad, India
D C Talsania
M. and J. Instt. of Ophthalmology, Ahmedabad
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Talsania D C, Mathur R N. Light differential threshold studies of reattached retina and macula. Indian J Ophthalmol 1984;32:525-7
|How to cite this URL:|
Talsania D C, Mathur R N. Light differential threshold studies of reattached retina and macula. Indian J Ophthalmol [serial online] 1984 [cited 2020 Jan 25];32:525-7. Available from: http://www.ijo.in/text.asp?1984/32/6/525/30860
Resettlement of a detached retina is the primary aim of the retinal surgery. Many a times patients are disappointed due to lack of functional recovery, when macula is detached for a long time, specially.
This study was aimed at finding out the functional recovery of reattached retina and macula in terms of Light Differential. Threshold (L.D.T.), as Kinetic field charting does not give the qualitative idea of vision at a particular point in consideration nor visual acuity is a direct guide of macular recovery as it could be parafoveal or para macular acuity.
| Materials and methods|| |
This study comprises of15 cases of retinal detachment (R.D) and 10 normal subjects. The successfully operated cases of primary retinal detachment with macular involvement, repaired at least 3 months before and with no other gross pathology, were selected for this study. Static meridional perimetry was done on Goldmann's perimeter with method of limits in background of 31.5 apostilbs. The ratio of basic luminosity to background illumination was kept at 33. Static perimetry was done after 10 minutes of adaptation. The L.D.T. was assessed at 2° intervals on the selected meridians up to 10° and the results were plotted. 6 meridians were examined usually considering the site of maximum height of detached retina.
| Observations|| |
The study includes 10 males and 5 females, with age varying from 13 years to 64 years. Out of these, 12 cases had R. D. in right eye and 3 had in left eye. Two third of these cases bad partial R D. whereas one third of these cases had total R.D. All had macula detached. V.A. was in the order of PL, PR to counting fingers. Post operative V.A. [Figure - 1] was in the order of 6/60 to 6/24. Out of 15 cases 5 were operated within one week of visual loss and 10 were operated after I week of visual loss.
The average L.D.T. in these cases in 10° region was 1.455 log units (L.U.) and at 1° it was 1.770 L.U. whereas L.D.T. in normal subjects was 0.877 L.U. & 0.640 L.U. respectively i.e in the successfully operated cases of R D. in 10° region sensitivity was twice as low as compared to normal subjects and at 0°sub region it was thrice as low as the normal subjects
The group with pre-operative VA CF or better had more sensitivity at 0° as compared to the group with pre-operative visual acuity PL, PR whereas there was no significant difference in average LDT in 10° region in both groups.
Thus sensitivity decreases (i.e. LDT increases) markedly if a detached retina is not settled within one week of detachment.
I A. Chisholm  et al have studied 35 cases of settled retina with macular involvement and found that recovery was poorer with longer duration of pre-operative period of detachment. They also established that the macular recovery lags behind as compared to periphery and is very slow and over a very long period. Our finding are alike.
Ingrid Kreissig studied LDT of 266 cases of RD and the following graph [Figure - 2] was obtained in various groups according to extent of detachment with macular involvement.
Whereas our overall pattern was just the reverse
The reason could not be detected for the greater damage to foveal region than surrounding area.
J.L. Meneze of Valencia also studied LDT of 185 reattached cases and he found diversity of curve patterns including central and paracentral scotomas, flat or lowered macular tracings, total curve depression, parafoveal depression, etc. Anderson studied `contrast sensitivity and central vision in reattached macula' but their study presented no evidence for a selective vulnerability of specific contrast channels unrelated to acuity loss. In our study LDT was on the contrary minimum at 0° showing, inverted peak at macula.
Many authors , have studied post-opr. Visual acuity and established relation between factors affecting the visual acuity outcome after R.D. surgery however, Andherson C  says that Visual acuity is of less importance because it may not reflect functional recovery and sensitivity level of the macular region and therefore LDT study is a better parameter.
| References|| |
I. A. Chisholm, E., Mc Clure and W. S. Foulds, 1975, Trans of Ophthal. Soc. U, K., Vol. XC V, Pt. I.
Anerson, C, and Sjostrand, J., 1981, .Acta, Amer. J Ophthalmol., 59/2: 161.
Foulds, W., Reid, H. and Chisholm, I. A., 1972, Modern Problems in Ophthalmol. Vol. 12, p 49.
Gruppose, S. S., Arch, 1975, Ophthalmol 93:327.
[Figure - 1], [Figure - 2], [Figure - 3]
[Table - 1], [Table - 2], [Table - 3]