|Year : 1980 | Volume
| Issue : 4 | Page : 189-193
Developmental variations of peripheral retina
Manoj Shukla, OP Ahuja
A.M.U. Institute of Ophthalmology, J. N. Medical College, Aligarh, India
A.M.U. Institute of Ophthalmology J.N. Medical College Aligarh U.P
|How to cite this article:|
Shukla M, Ahuja O P. Developmental variations of peripheral retina. Indian J Ophthalmol 1980;28:189-93
Periphery of the retina is defined as an area which is located anterior to the globe's equator. This area presents with numerous individual physiological variations and is a site for a number of potentially dangerous pathological lesions. The developmental variations of peripheral retina have been described clinically, as well as histopathologically,. The present study was undertaken to study the different anatomical and physiological variations of the peripheral retina in an attempt to isolate them from pathological lesions.
| Material and methods|| |
The study was undertaken on 400 eyes of 200 subjects who were picked up randomly from general population and did not have any complaints related to a retinal disease. After a complete ocular examination the examination of peripheral retina of both eyes was undertaken with the help of a indentation indirect Ophthalmoscope after full dilatation of pupils. In certain relevant cases this part of the examination was supplemented by the posterior segment biomicroscopy with the help of a Goldman's 3-mirror contact lens. The findings were recorded on a conventional fundus topography charts.
| Observations|| |
Different developmental variations of peripheral retina were observed in 154 (38.5%) of 400 eyes. These variations present either as isolated findings or concurrently with one another were as follows
A - Variations of ora bays and teeth
B - Meridional folds
C - Granular tissues
A. Variations of ora bays and teeth
The variations of ora bays and teeth were seen in the form of large dentate processes, giant dentate processes and deep bays. These were present in 53 eyes (13.25%) of 29 individuals (14.50%) as shown in [Table - 1]. There was a significant tendency for bilateralism 72% cases.
Large dentate processes were the commonest being present in 48 eyes (90.57%) of 27 subjects (93.10%) followed by deep bays which were present in 39 eyes (73.58%) of 22 subjects (75.86%). Giant teeth were present in 10 eyes (18.87%) of 5 subjects (17.24%) as shown in [Table - 2]. All these variations of ora bays and teeth were found to have a marked predilection for the supranasal quadrant. The deep bays were present either singly or in pairs. In 21 subjects (95. 45%) they were found in association with large dentate processes or giant teeth [Figure - 1].
B. Meridional Folds
Meridional folds were observed in 51 eyes (12.75%) of 31 subjects (15.50%); being bilateral in 20 (64.52%) as shown in [Table - 1]. The number of folds per eye varied from one to three. Supranasal quadrant was most commonly involved. All of these folds were associated with suboral cystoid degeneration [Figure - 2]. No hole or tear was found to be associated with these folds.
C. Granular Tissue
Areas of granular tissue were observed in 80 eyes (20%) of 44 subjects (22%), being bilateral in 36 (81.82%). A total number of 202 granular tissues were observed varying from 1-11 in individual eyes at an average of 2.53 per eye.
Three morphological types of granular tissue were seen viz granular patch, globule, and tags or floaters. Granular patches appeared as small raised opaque areas with irregular but well defined border on the inner retinal surface [Figure - 3]. Areas of granular globule appeared as irregular round masses being smaller in diameter than the granular patches [Figure - 4]. The granular tags and floaters were the commonest types of granular tissues seen in our cases. They appeared as tiny elongated strands or pieces of tissues which protruded from the inner surface of retina [Figure - 4], being pigmented in many instances. They were present in 69 eyes (86.25%) of 38 subjects (86.36%) showing a significant tendency for bilateralism (31 subjects- 81. 5 8 %). The incidence and regional location of various types of granular tissues has been shown in [Table - 3][Table - 4]. It is clear from [Table - 4] that majority of granular tissues (92.57%) were located in the oral region. The post equatorial region was invariably free from this feature. In general, the granular tissue had a slight preference for the nasal half of the globe (69.80%). The quadrantic distribution of various types has been shown in [Table - 5].
| Discussion|| |
The diagnosis of developmental variations of the peripheral retina was made when a structure in the equatorial and specially in the oral zone appeared to be other than normal in size, shape and texture. A number of development variations were seen in the peripheral retina in the present study. A proper recognition of these variations is of immense significance so that pathological processes in this region may be adequately distinguished from these.
The presence of various forms of granular tissue was the commonest variation seen in 20% of the normal eyes without any predilection for any age or sex. Rutnin and Schepens found granular tissue in 55 eyes of 41 subjects out of 102 examined. In the present study all types of granular tissue were observed most frequently in the oral region (92.57%) with a preference for nasal half of the globe. Similar observations have been made by other workers,. Granular tissues are supposed to be innocuous embryonic remnants but according to Rutnin and Schepens, when present in the form of tiny tags or floaters may suggest localised vitreo-retinal degeneration and traction. It looks however, unlikely that vitreo-retinal adhesions would take place in such tiny isolated tags. Moreover, no retinal tears were found to be associated with the tapes in our series.
Variations in the size and shape of ora bays and teeth were observed in 13.25% of normal eyes. These were mainly in the form of large or giant dentate processes and deep bays. Other forms like enclosed bays, forked, ring and bridging dentate processes were described as rare findings.2'4 As reported by these workers we also found a strong predilection for these variation in the superonasal quadrant (94 34%).
Meridional folds of various sizes running in continuation with dentate processes were seen in 12.75% of normal eyes, the majority being bilateral and symmetrical. No relationship of these folds to any age or sex was observed. The folds were not associated with any evident vitreous traction or hole formation, although some grade of cystoid degeneration was almost invariably present. Rutnin and Schepens have reported a higher incidence of 27.50%. Presence of partial or complete thickness retinal breaks in association with meridional folds in living eyes has been described,,. Schepens however emphasised that even in the presence of a hole or tear, retinal detachment rarely followed.
These innocent folds have to be differentiated from the usually larger folds produced by frank vitreous!' traction in the region of vitreous base which may lead to retinal tears and detachment. For this reason these folds may preferably be called "meridional ridges" as suggested by Eisner. The developmental meridionali7folds are believed to be due to' ectopia of tissue caused by the displacement of excess retinal tissue on to the pars plana. This probably takes place in early foetal life.
| Summary|| |
The developmental variations of peripheral retina were studied in 400 eyes of 200 normal subjects, picked up randomly from general population. The peripheral retina is a seat of a number of developmental variations which occur in 38.5% of normal eyes. The developmental variations are mainly in the form of variations of ora bays and teeth, meridional folds and granular tissues, the last one being the commonest. The anatomical variations of peripheral retina have a predilection for suboral region in the nasal half of the globe.
| References|| |
|1.||Schepens, C.L. and Bahn, G.C., 1950 Arch. Ophthalmol, 44:677. |
|2.||Rutnin, U., and Schepens, C.L. 1967; Amer. J ophthalmol. 64:840. |
|3.||Straatsma, B.R., Landers, M.B. and Kreiger, A.E. 1968; Arch. ophthalmol. 80:3. |
|4.||Straatsma, B.R., Foos, R.Y., & Spencer, L.M. 1969; The retina-topography & Clinical Correlations. In Symposium on retina & retinal surgery, P. I, Saint Louis, C.V. Mosby, 1969. |
|5.||Teng, C.C., and Katzin, H.M., 1953, Amer. J. Ophthalmol, 36:169. |
|6.||Spencer, L. M.. Foos. R. Y.: and Straatsma, B.R. 1969; Trans. Amer. Acad. Ophthal and Otolaryingol 73:201. |
|7.||Schepens, C.L. 1952; Trans. Amer Acad. Ophthalmol. Otolaryngol. 56:398. |
|8.||Eisner, G. 1973; Biomicroscopy of peripheral fundus; At Atlas & Textbook, Springer Verlag, Berlin Heidelberg, New York, 1973. |
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]