Traditional cryotherapy of all avascular retina 

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... of prematurity (ROP) is a disease of pre- vention, and a timely and proper treatment is the key to success in the fight against this disaster. In the ninth decade of the last century, cryotherapy was star- ted to use for ROP treatment. This method gained the widest acceptance after Cryotherapy for Retino- pathy of Prematurity Cooperative Group (CRYO ROP CG) had published their results (1) and it became evident that this treatment methodology would allow for prevention of many children blindness cases. At the turn of the century, another treatment form – lasertherapy – gained a substantially wider application for treatment of the disease, especially in the western countries (2). It was being stated that lasertherapy resulted in less complications, and provided blindness prevention as effective as cryotherapy. Over the years there has been a consistent improvement using both therapy modalities, but none of them resulted in a 100% success rate. However, the total cost of requi- red equipment for lasertherapy is much higher than for cryotherapy, and this factor is essential for the poor developing countries of the world, where the epidemic wave of ROP is just starting. In this paper, we present our unique modified cryotherapy modality for Zone II ROP treatment, which enables a complete prevention of blindness caused by this kind of disease. 2159 infants were screened for ROP in Vilnius Uni- versity Children Hospital from January 1995 to De- cember 2003. All these infants were outborn. Thres- hold ROP was diagnosed in 320 infants (14.8%). Of them, 182 eyes had Zone I ROP, and for 445 eyes Zone II ROP was diagnosed. All Zone II ROP (Fig. 1) threshold infants underwent cryotherapy. One in- fant died during operation because of multiple conge- nital malformations and was excluded from result eva- luation. All screening, treatment and postoperative fol- low-up procedures were performed by the same two ophthalmologists (RB and RS). All infants had their threshold status confirmed by both examiners. The presence of retinopathy and indications for treatment were in accordance with International Classification of ROP and CRYO ROP CG (3, 1). Posterior Zone II cases were ascribed to Zone II. The criteria for unfavorable outcome corresponded to those of CRYO ROP CG study, including macular fold, retinal de- tachment, or retrolental fibroplasia (1, 3). Treatment was administered within 24–48 hours after diagnosis. Cryotherapy was always carried out in the operating room using general anesthesia. Cryoequipment (Erbe, Germany) with a cataract probe and binocular indirect ophthalmoscope (Kee- ler) with +20 and/or +28 D lenses were used for all procedures (4). The pupils were dilated by 0.5% Tro- picamide drops. Maximum mydriasis was obtained with additional use of 2.5% Neosynephrine, 1% Cyclopent- holate or 0.1% Atropine solutions. Ung. Tetracyclini or ung. Tobramycini were used at the end of the pro- cedure. Postoperatively, steroid drops were instilled four times a day and mydriatics were applied (2 times a day) for 2–3 weeks. All infants were reexamined after the procedure in 6–10 days. Follow-up examina- tions were performed biweekly until disease regres- sion. The second or third treatment procedure (if ne- cessary) was performed within 10–14 days after the previous one. The structural (anatomical) outcome was evalua- ted in treated infants at least 6 months after the pro- cedure. The traditional (recommended by CRYO ROP CG) modality – treatment anterior to the ridge (Fig. 2) – was used in 1995. Our modified cryotherapy consisted of two rows of cryoapplications: one row on the ridge and the other row anterior to the rid- ge. Not the whole area of the anterior avascular re- tina up to ora serrata was covered by cryoapplica- tions (Fig. 3). This kind of treatment has been ap- plied in eyes with Zone II ROP from 1996 (5, 6). In order to make cryotherapy as effective as pos- sible and as harmless as possible for the baby, we have introduced a few additional improvements of the cryoprocedure from the very beginning of our work: 1. The so-called “four hands technique”. The cry- otherapy procedure is performed by two physicians. The first one performs ophthalmoscopy holding a lens in one hand and drops BSS solution onto the eye during the thaw period. The second physician, using a cryoprobe, indents the exact place, and with a gentle manipulation with a strabismus hook in the other hand brings the avascular zone into view, or regulates the position of the lid speculum. 2. Small gauze is placed between the eyelid and the cryoprobe to prevent the eyelid from freezing. 3. Dropping of a balanced salt solution on the cornea and cryoprobe after every cryoapplication al- lows for shortening the unfreezing period and pre- vents the eyelid and corneal damage. Using the traditional cryotherapy recommended by CRYO ROP CG, adverse outcome was diagnosed in 3 eyes. Favorable results were obtained in 52 eyes (94.5%). Modified cryotherapy was successful in 390 eyes (Table 1). None of the eyes needed more than two treat- ments in modified cryotherapy (Table 2). All eyes that needed the second procedure in the modified cryotherapy group belonged to posterior Zone II. Al- so, skipped areas observed on follow-up near the ridge were treated. Small ridge hemorrhages without sequela for out- come were observed in 18.2% (10/55) of eyes trea- ted by traditional cryotherapy and in 11.8% (46/390) of eyes treated by modified cryotherapy. None of the complications described in CRYO ROP CG stu- dy, such as tumor like conjunctival hemorrhages and unintended conjunctival lesion, were observed in our study ...