Indian Journal of Ophthalmology

ORIGINAL ARTICLE
Year
: 1995  |  Volume : 43  |  Issue : 2  |  Page : 59--61

Retinopathy of prematurity: A study


Lingam Gopal1, T Sharma1, Sudha Ramachandran2, R Shanmugasundaram2, V Asha1,  
1 From Vision Research Foundation, Sankara Nethralaya, 18 College Road, Madras 600 006, India
2 Child Trust Hospital, Madras, India

Correspondence Address:
Lingam Gopal
From Vision Research Foundation, Sankara Nethralaya, 18 College Road, Madras 600 006
India

Abstract

A total of 50 infants of less than 2000 gm birth weight were screened for retinopathy of prematurity (ROP) by binocular indirect ophthalmoscopy. The incidence of ROP was found in 19 patients (38%). Of these, 8 patients (16 eyes) had threshold disease. Significantly, occurrence of threshold ROP was seen in both 1600 gm birth weight in one infant and in the absence of oxygen administration in 2 infants. Ten of the 16 eyes underwent therapeutic intervention while 6 eyes did not receive treatment for lack of consent from the parents. The treatment consisted of indirect laser photocoagulation (8 eyes) and transconjunctival cryopexy (2 eyes). Good regression of the disease (favourable outcome) was noted in all the treated eyes.



How to cite this article:
Gopal L, Sharma T, Ramachandran S, Shanmugasundaram R, Asha V. Retinopathy of prematurity: A study.Indian J Ophthalmol 1995;43:59-61


How to cite this URL:
Gopal L, Sharma T, Ramachandran S, Shanmugasundaram R, Asha V. Retinopathy of prematurity: A study. Indian J Ophthalmol [serial online] 1995 [cited 2024 Mar 28 ];43:59-61
Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?1995/43/2/59/25258


Full Text

Retinopathy of prematurity (ROP) is a disease related to low birth weight, prematurity, oxygen administration, and other unidentified factors. The incidence of this disease is paradoxically increasing with the improved neonatal care, as a result of the improved survival of the premature infants. In the Indian subcontinent, ROP has not been a major problem until recently. In this study, all premature infants of less than 2000 gm birth weight admitted under the care of a single neonatologist (RS) were examined by a single observer (LG). The clinical profile, the management offered and the outcome of the treatment are discussed in this communication.

 MATERIALS AND METHODS



This was a prospective study and involved examination of all premature infants admitted at Child Trust Hospital under the care of a single neonatologist (RS). The initial examination was carried out between 4th and 7th week after birth. The ophthalmic examination was carried out by a single ophthalmologist (LG). Detailed history included the birth weight, gestational age, the postnatal problems and their management. A special note was made of the oxygen administration and blood transfusions.

The anterior segment was evaluated by the magnification offered by the +20D lens of indirect ophthalmoscope to look for anterior segment plus disease and persistent pupillary membrane. Pupillary dilatation was done with a mixture of 2.5% phenylephrine and 1% tropicamide instilled twice at intervals of 15 minutes. The child was kept comfortable with warm cloth cover and mummified, thus restraining the hands. An Alfonso speculum was used to separate the lids. Fundus was examined with binocular indirect ophthalmoscope and +20D condensing lens. Scleral depression was performed using the infant scleral depressor devised by one of the authors (LG). The depression was carried out transconjunctivally after topical anaesthesia using 2% lignocaine eye drops. The findings were noted as per the guidelines of International Classification of Retinopathy of Prematurity (ICROP).[1],[2]

Infants with normal vascularization of the fundus upto the periphery were not re-examined. Infants with peripheral avascular retina but no clinical ROP and those with prethreshold ROP were re-examined at weekly intervals. The prethreshold ROP cases were followed until they progressed to threshold ROP in which case they were treated or until there was total regression. Threshold ROP was treated, when found, either at first examination or on follow-up. Indirect ophthalmoscopic argon laser photocoagulation was the modality of choice in treating 8 eyes. However, transconjunctival cryo was done in two eyes where the pupil did not dilate adequately. The treated eyes were re-examined every week till total regression was noted. In 2 cases, transconjunctival cryo therapy was done as additional treatment to extreme peripheral areas of avascular retina, when the laser photocoagulation did not bring about the desired regression. Eyes presenting with peripheral avascular retina but no clinical ROP were similarly followed up weekly till either normal vascularization took place, or ROP developed.

Indirect ophthalmoscopic laser (Coherent Novus 2000, Palo Alto, Ca) was done under topical anaesthesia using Alfonso speculum. Scleral depression with infant scleral depressor aided the laser photocoagulation. The avascular retina anterior to the ridge was treated, carefully avoiding treatment of the ridge itself. Cryopexy was performed always under general anaesthesia. Regular retina cryo probe (Frigitronics, Connecticut) was utilized transconjunctivally. The conjunctival incision was not needed in patients reported here.

 RESULTS



A total of 50 infants were screened from November, 1992 to January, 1994. The birth weights ranged from 750 to 2000 gm (average, 1477.6 gm). The gestational age ranged from 27 to 37 weeks (average, 32.4 weeks). Retinopathy of prematurity was detected in 19 patients (38%). The incidence of ROP versus birth weight and gestational age are detailed in Figs.1 and 2, respectively.

The initial examination was done between 4 and 7 weeks after birth (average, 5.1 week). In 18 patients, ROP was detected at the first examination. In one infant, the retinal periphery was avascular at the first examination but developed threshold ROP within 2 weeks.

The disease was symmetrical in 13 cases and asymmetrical in 6 cases; 4 of which had unilateral involvement, resulting in 34 eyes with ROP. None of the unilateral cases had severe (Plus) disease. The staging of disease at detection of ROP is shown in the Table.

Of the 50 cases screened, 33 had a history of oxygen administration. Of these; 17 (51.5%) developed ROP.

Viewed differently, of the 19 cases with ROP, 17 had history of oxygen administration. Significantly, 2 patients developed ROP even in the absence of oxygen administration. Of the 34 eyes with ROP, 16 (47.1%) developed threshold disease either at initial examination or at follow-up. The 8 cases (16 eyes) that developed threshold ROP were analysed separately. Their birth weights ranged from 1100 to 1600 gm. (average, 1394 gm) which is not significantly different from the average birth weight of all the infants screened (1477.4 gm), as well as the average birth weight of all patients that developed ROP (1355.33 gm). However, all the infants that developed threshold ROP had oxygen administration; and 6 out of 8 had blood transfusions. Of these 16 eyes, 10 received treatment for the threshold disease; in other 3 patients (6 eyes) treatment was not provided for lack of consent from parents. The remaining 18 eyes had spontaneous regression observed on follow-up, with no sequelae.

Of the 10 eyes that were treated for the threshold disease, laser indirect photocoagulation (LIP) was done in 8 eyes as the first modality of treatment. In 2 eyes transconjunctival cryo therapy was done as first treatment. Supplemental cryo therapy was done in 2 eyes since LIP did not give the desired result. All the treated eyes had good regression of the disease (favourable outcome). 'Favourable outcome', as defined by the cryo ROP study[3] is anything other than retinal detachment involving the fovea, a retinal fold involving the fovea, or a retrolental mass. Sequelae were seen only in 3 eyes in the form of small persistent fibrous ridge of no more than 2 o'clock hours. There were no cases with ectopic macula or folds.

 DISCUSSION



Terry[4] first reported retrolental fibroplasia in premature infants. With implication of oxygen as the causative agent and its subsequent curtailment, the infant mortality rate increased.[5] Efforts to correlate the oxygen concentration being administered with the occurrence of ROP have not succeeded. Heath[6] introduced the term retinopathy of prematurity, which is applicable to all the stages of the disease unlike retrolental fibroplasia that was applicable to only to the stage V disease. The international classification for ROP has been accepted as the standard for documenting and describing this disease.[1],[2]

As of now, ROP has not been reported as a serious challenge in India. With improving neonatal care and increasing survival of low and very low-birth weight children, the incidence is expected to increase exponentially in the near future. Routine evaluation of preterm infants at risk is not, as yet, being done due to lack of awareness of this potentially blinding problem. Hitherto, most cases were being referred to the ophthalmologist with stage V ROP at which stage prophylactic treatment cannot be offered and surgical treatment is successful only in a small number. The present study has shown the significant incidence of ROP in a sample population.

As shown in the literature,[7] the incidence of ROP is higher with the lower birth weights, but occurrence of threshold ROP even at a birth weight of 1600 gm is significant. Hence, screening of infants should be done upto 2000 gm birth weight.

In view of the significantly different funduscopic picture in the infants, ophthalmologists should become familiar with the appearance of normal retinae of infants, to facilitate easy diagnosis of ROP. No anaesthesia is required or desirable for routine screening of the infants. Since these infants do not move their eyes much, stabilizing the head alone allows adequate examination. Use of binocular indirect ophthalmoscope is a necessity and in our hands the Alfonso speculum[8] was found extremely useful. Scleral depression is occasionally indicated to visualize the extreme periphery. This has been made easy with the infant scleral depressor that the authors have devised.[9] The depressor is used over anaesthetised conjunctiva.

Threshold ROP has been defined by the ICROP as stage III plus disease of 5 continuous or 8 discontinuous clock hours. Treatment with cryo was recommended at or beyond this stage of disease. Although cryo was the modality used and tested extensively,[10] photocoagulation has been tried as early as 1968 in Japan.[11] With the advent of indirect ophthalmoscopic delivery system, laser photocoagulation has become increasingly the first choice of treatment[12] as it has several advantages. It obviates the need for general anaesthesia; it is associated with significantly less morbidity and there is no external reaction such as conjunctival chemosis. Use of infant scleral depressor has permitted us to treat right upto the ora serrata with indirect laser photocoagulation. With argon laser photocoagulation, the only difficulty is the presence of tunica vasculosa lentis. Hittner et al (quoted by Isenberg)[13] have described and graded the anterior vascular capsule (tunica vasculosa lentis) and shown it to correlate well with the gestational age. Hence, significant remnants of the same can be expected in some of those infants born premature. The haemoglobin in the blood column of the blood vessels can absorb argon laser energy and due to their proximity to the anterior lens capsule could lead to the lenticular burns. Diode laser in this situation is an obvious advantage.[14]

The results of the treatment have been very satisfactory in this small series. Part of this near 100% success is due to the absence of Zone I disease in this series and early identification of threshold disease. Absence of Zone I disease is probably related to the poor survival rate of very low- birth weight infants (<1000 gm).

References

1Committee for the Classification of Retinopathy of Prematurity: An International Classification of Retinopathy of Prematurity. Arch Ophthalmol 102:1130-1134, 1984.
2An International Classification of Retinopathy of Prematurity II: The Classification of Retinal Detachment. Committee for the Classification of Late Stages of Retinopathy of Prematurity. Arch Ophthalmol 105:906-912, 1987.
3Cryotherapy for Retinopathy of Prematurity Co-operative Group: Multicentre trial of cryo therapy for retinopathy of prematurity. Preliminary results. Arch Ophthalmol 106:471-479, 1988.
4Terry TL. Extreme prematurity and fibroplastic over growth of persistent vascular sheath behind each crystalline lens 1 Preliminary report. Am J Ophthalmol 25:203-204, 1942.
5Eichenbaum JW. In: Eichenbaum JW, Mamelok AE, Mittl RN, Orellana J (ed), The Oxygen Era in Treatment of Retinopathy of Prematurity. Chicago, Year book Medical Publishers Inc., pp. 30, 1990.
6Heath P. Pathology of the retinopathy of prematurity: Retrolental fibroplasia. Am J Ophthalmol 34:1249-1268, 1951.
7Flynn JT. Retinopathy of prematurity. In: Eichenbaum JW, Mamelok AE, Mittl RN, Orellana J (ed), Treatment of Retinopathy of Prematurity. Chicago; Year Book Medical Publishers Inc., pp. 97, 1990.
8Orellana J. Examination of the premature infant. In: McPherson AR, Hittner HM, Kratzer FL (ed), Retinopathy of Prematurity: Current Concepts and Controversies. Toronto BC Decker Inc., 1986, pp. 13.
9Kumar KS, Gopal L, Badrinath SS. Infant Scleral Depressor. Retina 12:74, 1992.
10Cryotherapy for Retinopathy of Prematurity Co-operative Group - Multicentre trial of cryo therapy for retinopathy of prematurity - One year outcome - Structure and function. Arch Ophthalmol 108:1408-1416, 1990.
11Nagata M, Kobayashi Y, Fukuda H, Suekane K. Photocoagulation for the treatment of retinopathy of prematurity. Jap J Clin Ophthalmol 22:419-427, 1968.
12McNamarra JA, Tasman W, Brown GC, Federman JL. Laser photocoagulation for stage 3+ retinopathy of prematurity. Ophthalmology 98:576-580, 1991.
13Isenberg SJ. In: The Eye in Infancy. St. Louis, C.V. Mosby, 1994, pp. 45-46.
14Benner JD, Morse LS, Hay A, Landers III MB. A comparison of argon and diode photocoagulation combined with supplemental oxygen for the treatment of retinopathy of prematurity. Retina 13:222-229, 1993.