Re: Chiang et al.: International Classification of Retinopathy of Prematurity, Third Edition (Ophthalmology. 2021;128:e51–e68)

Abstract

TO THE EDITOR: In their article, Chiang et al 1 have updated the International Classification of Retinopathy of Prematurity (ICROP) to improve objectivity of finding, as well as to encompass clinical variations observed in regression or reactivation of retinopathy of prematurity (ROP), particularly after treatment with anti-vascular endothelial growth factor. The authors have subclassified zone II as anterior and posterior to identify the more serious disease in posterior zone II. However, the standard of care for the disease in both the zones is likely to be laser photocoagulation. To best of our knowledge, there is currently no study that has attempted to compare the outcomes of treatment between the anterior and posterior locations of zone II. In contrast, ROP in zone I, particularly posterior zone I, has been shown to have poor structural outcomes with laser monotherapy as opposed to a combination therapy with anti vascular endothelial growth factor and laser photocoagulation. 2,3 Kychenthal et al 4 have defined posterior zone I as a circular area centered on the optic nerve head, with a radius being the distance between the center of the optic disc and the fovea. However, this subdivision of zone II has not been used universally for documentation, sometimes referred to as the half zone. We suggest, similar to zone II, that zone I also be subdivided into anterior and posterior with reference to the fovea. This subdivision will not only ensure the objectivity of documentation of disease involving zone I, it will also have direct implications for deciding the appropriate treatment and prognosis based on currently available evidence.In the current classification, aggressive posterior ROP (APROP) has been replaced by aggressive ROP. For this change, the authors have cited a series of "fulminate ROP" by Shah et al. 2 The description of fulminate disease given by the authors in this article is very typical of APROP as described in ICROP 2. In their description, it is a disease that usually occurs within a definite zone, extending nasally 2 to 3 diameters from the disc margin and edge of the macula temporally. This area roughly corresponds with posterior zone I as described by Kychenthal et al. 4 The average gestational age and birth weight of infants in this series was more than typically described for fulminate ROP by others authors. Shah et al concluded that the zone I ROP occurred in babies with higher gestational ages and birth weights in India than in Western countries. We feel the word "posterior" in APROP can be retained because it is an integral part of disease description.

Systematic review of the guidelines for retinopathy of prematurity

“…The most common indication was type 1 ROP in zone I of any stage with or without plus disease (7 documents). 25,28–30,32,42,43 In other countries, anti-VEGF agents were also recommended for other indications, including: stage 3 with plus ROP in zone I, 26,33 type 1 ROP in zone I when laser therapy fails 31 or is contraindicated, 38 type 1 ROP in any zone when laser therapy fails 32,35 or is contraindicated, 29,32,35,38,40 type 1 ROP in any zone when primary laser 28 or surgical treatment 32 are not available, type 1 ROP in any zone in stage 4–5 with vitreoretinal membranes, 33 any case of aggressive ROP (A-ROP) 29,32,33,40,42,50 or only when laser therapy fails. 31 Some authors recommended using anti-VEGF agents in type 1 ROP involving zone II and III 43 or posterior zone II with or without plus disease 29 or only when plus disease is present.…”

Clinical characteristics, risk factors and short-term prognosis of retinopathy of prematurity complicated with retinal hemorrhage

“…All included premature infants were examined by RetCam- II fundus digital camera, and the ROP condition was graded according to the International Classification of ROP (ICROP). 7 Treatment indications were carried out in accordance with the standard of Early Treatment for ROP Collaborative Group (ET-ROP), 10 and the treatment objects included: (1) Threshold lesions: Stage 3 lesions in Zone I and Zone II for 5 consecutive hours or 8 cumulative hours, Simultaneously with Plus lesions. (2) Pre-threshold lesions Type 1: ROP of each stage in Zone I with plus lesions, or Stage 3 lesions without plus lesions, or Stage 2 or 3 ROP in zone II with plus lesions.…”

“…6 In the current international classification standards, the severity of retinopathy is mainly described according to the degree and extent of abnormal vascular proliferation and the presence of additional lesions. 7…”

Quantitative vascular outgrowth and anatomic and refractive outcomes of eyes treated with bevacizumab in posterior zone Ⅰ

“…7–9 Although Zone Ⅰ subgroups have not been defined in the ICROP reports, the definition of posterior zone Ⅰ was designated for eyes with a posterior border of retinal vascularization that is shorter than the optic disc-to-fovea distance (ODFD). 9,10…”

“…[7][8][9] Although Zone Ⅰ subgroups have not been defined in the ICROP reports, the definition of posterior zone Ⅰ was designated for eyes with a posterior border of retinal vascularization that is shorter than the optic disc-to-fovea distance (ODFD). 9,10 In studies evaluating posterior zone Ⅰ eyes as a subgroup, it has been reported that the majority of the posterior Tertiary ROP Clinic, Health Science University Kanuni Sultan Suleyman Training and Research Hospital, Istanbul, Turkey zone Ⅰ cases have unfavorable anatomical results after laser treatment. 9,11 Although better anatomic and refractive results have been reported in zone Ⅰ with intravitreal bevacizumab (IVB) in many reports, as far as we know, the outcomes of posterior zone Ⅰ cases with IVB treatment have not yet been reported.…”