|Year : 1981 | Volume
| Issue : 4 | Page : 339-343
Restoration of ocular structure and function following detachment surgery
Swapna Roy, Bijayananda Patnaik, Rajinder Kalsi
Department of Retina Care, Guru Nanak Eye Centre, Maulana Azad Medical College New Delhi, India
Guru Nanak Eye Centre, MAMC, New Delhi-1100029
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Roy S, Patnaik B, Kalsi R. Restoration of ocular structure and function following detachment surgery. Indian J Ophthalmol 1981;29:339-43
|How to cite this URL:|
Roy S, Patnaik B, Kalsi R. Restoration of ocular structure and function following detachment surgery. Indian J Ophthalmol [serial online] 1981 [cited 2020 Jun 5];29:339-43. Available from: http://www.ijo.in/text.asp?1981/29/4/339/30927
The aim of this presentation is to evaluate the restoration of the ocular functions following modern detachment surgery.
| Materials and methods|| |
Twenty nine operated cases of rhegmatogenous retinal detachment selected at random during the second half of 1977 were the subject for this study.
Patients were assessed both preoperatively and postoperatively on following parameters: Corneal vitality assessed by measurement of corneal sensitivity by anaesthesiometer staining with fluorescein and presence or absence of oedema. Corneal thickness by pachometer, Corneal curvatures by keratometer, depth and content of anterior chamber, angle of the anterior chamber, biomicroscopy of iris and lens. Intraocular pressure by goldman applanation tonometer visual acuity Field of vision by Goldman's perimeter.
All these examinations were carried out preoperatively and twice a week after operation during the patients' hospital stay. There after at monthly intervals.
| Observations and comments|| |
Depth of Anterior Chamber (D.A.C.)
The majority of cases (83%) showed a decrease of the depth of anterior chamber which was of an average of 0.39 mm. which is in conforming with other workers' observations.
Since increase in corneal thickness averaged at 0.05 mm. the shallowing of the anterior chamber was most probably due to anterior displacement of the lens-iris diaphragm.
This change also was temporary. The majority (76%) returned to pre-operative value within 3 months and 4 (15%) more within 0.1 mm of preoperative reading. The magnitude of decrease in the depth of A.C. in encircling procedure (1.36 min) was some what higher than local procedure (0.238 mm). However the difference was not statistically significant (p>0.70).
Interestingly the shallowing of the DAC did not affect the visibility of chamber angle as viewed through a gonioscope.
Changes in the angle of the anterior chamber
Only 3 out of 29 cases (10.45%) cases showed a narrowing of the angle of anterior chamber that too within one grade.
Though some have encountered angle closure glaucoma following detachment surgery not one case has been encountered in this clinic and this series. Only 2 cases, both post traumatic cases of retinal detachment, had developed rise in intraocular pressure postoperatively, but no angle closure. They were easily controlled by Acetazolamide therapy.
The intraocular pressure of the eye with retinal detachment was generally lower than the fellow normal eye (average : 11.7 mmHg). Intraocular pressure in 17 eyes was between 3 to 10 mmHg, in 5 between 11-15 mmHg, in one 21 mmHg and in 2 it was higher than 21 mmHg. The last 2 cases were cases of post traumatic detachments.
When only cases where retina had settled were studied in the immediate postoperative period there was fall in I.O.P. from preoperative value in 75% of cases and increase in remaining 25%. During the follow up period: 20% had attained their preoperative values, 35% had increased and 45% still showing a lower value. The average I.O.P of the operated eye (11 mmHg) was fractionally higher than the average I.O.P. of the normal fellow eye (10.9 mmHg). Thus there was no definite response in 1.0 P. in detachment surgery.
While many have observed that the I.O.P. immediately following surgery is lows, and remains low even after 6 months,,. Others have recorded enormous increase in I.O.P. immediately following surgery, spontaneously failing to pre-operative level after the 12th day.
Thus while in the majority I.O.P. is likely to remain low after operation some may show an increase. The difference in observation by different workers may have something to do with case selection or operative technique.
The average preoperative I.O.P. of cases where retina did not settle (5.66 mmHg) was significantly lower than that of those cases where it settled (10.45 mmHg). The cases of hypotony, especially of acute hypotony with or without choroidal detachment have been seen to do badly after detachment surgery.
The average corneal thickness was 0.55 mm. All the 29 cases studied showed an increase in corneal thickness post operatively which varied from 0.01 mm to more than 0.10 mm with an average of 0.05 mm. 18 case had an increase of less than 10%, 10 cases 10-20% and 1 case more than 20%.
Though the classical signs of corneal oedema were not observed, a definite increase in corneal thickness in all cases after operation, would indicate certain degree of corneal oedema in each case.
The increase in thickness in all cases irrespective of type of surgical procedure, sectorial or encircling. Cyro or diathermy, with or without drainage of fluid may mean that any operation on the sclera may lead to corneal oedema, or may mean that peritomy is the cause of oedema. Besides, long exposure of the cornea may lead to certain degree of devitalisation of the cornea leading to corneal oedema.
The oedema however was transient, the thickness coming back to normal within 1 month in 20 out of 29 cases. Fiore and Newton (1970) have recorded transient thickening of the cornea following scleral buckling procedure. They have noted that the normalisation takes about 2 months.
Corneal Curvature (27 cases studied
There was a definite tendency for one of the axes to get aligned across the buckle. In 19 (70.4%) one axis passed over the buckle and in 7 (26%) the axis moved towards it.
The follow up (4-20 weeks) studied revealed that in over half (55.5%) there was a tendency for the reversal of axis to the original meridian.
The change of refractive power of cornea varied from +0.12D to -3.0D, with the vast majority (81.5%) showing a change of less than 1.OD. In the majority (74%) there was a decrease in induced astigmatism. Only in 5 cases an increase was noted.
The difference of astigmatism induced by radial against circumferential buckle in this series was negligible. This may be due to the globe conforming solid silicon buckle used in this series.
The corneal sensitivity was depressed all over the cornea in all cases (19) operated with an encirclege procedure with 360 degrees peritomy. On the other hand cases operated with a local procedure (9 cases) with a 180 degrees peritomy the depression of corneal sensation was confined to the concerned sector. In an encircling operation the depression of corneal sensation was deep in the sector of the cornea corresponding to the scleral surgery (noted in 3 cases).
The depression in sensitivity was not dependent on the type of retinopexy used. The sensitivity improved with time, it had not reached the preoperative level in 4-20 weeks of follow up. Gotzowa similarly observed depression of corneal sensitivity mainly to the sector corresponding to the area of operation. It appears that the depression of corneal sensitivity to a great degree was caused by the peritomy. This is not surprising in view of the fact that perilimbal conjunctival nerves form an important part of corneal sensory system.
The additional gross diminution of corneal sensation in the sector where sclera was operated upon also is understandable in that ciliary nerve supply of the concerned sector would be expected to be affected by the surgical procedure on the sclera.
However, unlike others, we have found no relationship with diathermy and diminution of corneal sensation. This may be because of our precise and conservative approach to diathermy where the application was kept to the minimum in number and degree. As a result the tissue damage across the sclera was minimal.
Recovery of corneal sensation back to normal seems to take a long time. It had not reached normal level in 20 weeks. Bietti and Pannarale observed that it takes months of years to come back to normal.
This should have an important bearing in providing protection to the cornea after operation and even on decision to use or not to use contact lenses after detachment operation.
When stained with fluorescein 16 out of 20 cases (80%) operated with encircling procedure and 6 out of 9 cases (66.6%) operated with local procedure showed staining in the post operative period. Usually the staining cleared in I to 3 months. In 2 cases it had not cleared even by then. None of them had staining before operation. Thus corneal staining becomes an important parameter to assess the normalisation of corneal vitality.
In all 3 cases in this series where the macula was not detached, the preoperative vision was maintained following the operation. It would therefore be safe to assume that modern operative technique per se do not adversely affect the visual acuity.
In the remaining 17 cases where the macula was detached preoperatively the average increase in visual acuity (V.A.) was 16.5%. The increase in V.A. in cases with local buckle was somewhat better than those operated with encircling procedure (21.75 against 16.6%). The difference however was not statistically significant.
Though it is generally believed that the visual recovery drastically diminishes when the macula remains detached for more than 8 weeks and longer the retina remains detached worse is the expectation in visual acuity, no clear relationship between duration of detachment and degree of visual acuity improvement could be established. There seem to be other factors, specially the type of vitreo-retinal degeneration and preoperative state of macula which are perhaps of greater importance than the duration of detachment.
The age of the patients does not seem to have any bearing on the improvement of visual acuity. Improvement in vision among aphakics (23%) and emmetropics (19%) seem to be more than myopics (8%). This could be explained in terms of pre-existing myopic macular degeneration and poor preoperative vision.
The visual fields of all 11 cases tested showed an improvement after reattachment surgery. However, 2 cases showed a constriction of the field after 4 months of operation. One of us (B.P.) has observed such a phenomenon in occasional cases when field is charted on long term follow up. The explanation is not known.
Two cases in this series have shown signs suggestive of anterior segment ischaemia. In both encircling was effected with silicon bands over extensive intrascleral grooved silicon tire implants. In one radiofrequency diathermy was used on the resected bed and did not involve long posterior ciliary arteries. In the other cryopexy was useA. The intraocular pressure in the second case was fluctuating between hypotony to ocular hypertension. No extraocular muscle were detached. Thus it appears encircling procedures with massive scleral work could lead to anterior ischaemic changes. Rise of intraocular tension in the postoperative period also could be instrumental in ischaemic changes.
Massive vitreous retraction (M.V.R.) is now a well recognised serious element in certain types of Retinal detachments carrying poor prognosis. Local procedures ar. often found inadequate. Excessive diathermy seem to hasten and worsen vitreous retraction. In this series in all cases of M.V.R. encirclage was the primary procedure and diathermy was not used. Yet, M.V.R. has been the commonest cause of failure in this series (8 out of 9 cases).
| Summary|| |
- Immediate mobilisation following modern retinal detachment surgery permitted extensive postoperative investigations on visual functions, state of the cornea, anterior chamber and intraocular pressure.
- Modern surgeries or retinal detachment, mutilating as it may seem, do not adversely affect the visual acuity where macula had not detached. Improvement of visual acuity is more in asphakics and emmetropics than myopics.
Visual fields improve to variable extent but occasionally shows definite constriction after 4 months.
- Corneal sensation is invariably depressed-probably subsequent to peritomy and scleral surgery. Recovery is slow. Punctate staining of the cornea is common after operation and takes l to 3 months to disappear. There is invariably an increase in corneal thickness indicating some degree of corneal oedema. These could be important in postoperative care of cornea.
- The induced astigmatism is of small order. One of the axes either passes over or move towards the buckle.
- In most cases the depth of the anterior chamber decreases after surgery by a forward displacement of lens iris diaphragm. This did not affect the angle materially nor lead to angle closure glaucoma.
- Massive vitreous Retraction was the commonest cause of failure in this series.
- Encircling procedures with extensive scleral dissection by themselves may be responsible for ischaemic features in the anterior segment.
- Because of a relatively small series the conclusions have to be considered tentative.
| References|| |
Syrdalen, P. 1970: Acta Ophthalmologica, 48:1024.
Fiore, J.V. and Newton J.C.: Arch. Ophthalmol 84:284.
Cunha, S.L. : 1967 Ophthalmologica, 153:164.
Urrets-Zavalia A.Jr. 1968 New and Controversial Aspects of Retinal Detachment (Ed. McPherson Hoebar Medical Division, U.S.A., 1968). pp. 289.
Gotzowa, R. : 1972 Klin. Oczna, 42:1201.
Pannarale, M.R. and Pannarale, G. 1965 Boll. Ocul. 44:929.
Bietti and Pannarale: New and controversial Aspects of Retinal Detachment. (ed. McPherson; Hoeber Medical Division, U.S.A. 1968). pp. 310-311.
Patnaik, B. : 1967 Investig. Ophthalmol 6:610.
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