Treatment for non-type 1 retinopathy of prematurity by intravitreal injection of anti-vascular endothelial growth factor drugs

Abstract

Background: To explore clinical characteristics and treatment reasonsfor intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) drugs in the treatment of non-type 1 retinopathy of prematurity (ROP).

Methods: A retrospective study was conducted to screen the non-type 1 ROP from the collected ROP patients who received intravitreal injection of anti-VEGF drugs in Henan Eye Hospital from September 2018 to June 2021.

Results: A total of 138 ROP cases (262 eyes) were included in this study, including 39 cases (28.3%) 65 eyes (24.8%) were the non-type 1 ROP. Compared with the type 1 ROP group, the non-type 1 ROP group had slightly later treatment time (39.8±2.7 weeks vs 38.1±2.6 weeks, P<0.05) and a higher proportion of fusion protein drugs (87.2% vs 54.5%, P<0.05). After intravitreal injection of anti-VEGF drugs, 27 eyes (41.5%) were cured and 38 eyes (58.5%) were improved in the non-type 1 ROP group, without recurrence and aggravation cases. There were more lesions in zone II (63 eyes, 96.9%), with stage 2 (40 eyes, 61.5%) and stage 3 (23 eyes, 35.4%), and 58 eyes (89.2%) showed pre-plus in the non-type 1 ROP group. Treatment reasons included pre-plus in 58 eyes (89.2%), ridge aggravation in 22 eyes (33.8%), simultaneous treatment of the contralateral eye in 9 eyes (13.8%), no regression of lesions in persistent stage 2 or 3 over PMA 44 weeks of follow-up in 8 eyes (12.3%), and logistical considerations in 4 eyes (6.2%).

Conclusions: Considering some peculiar clinical characteristic, treatment by intravitreal injection of anti-VEGF drugs may be considered carefully for some non-type 1 ROP in critical conditions.

Introduction

Retinopathy of prematurity (ROP) is a proliferative retinal vascular disease that occurs in premature and low-weight infants, and it most afflicts both eyes and may cause retinal detachment and blindness. Current treatments of ROP include laser photocoagulation and intravitreal injection of anti-vascular endothelial growth factor (VEGF) drugs. The Early Treatment for Retinopathy of Prematurity (ETROP) and the latest expert consensus or guidelines recommend treatment for type 1 ROP and close follow-up for Type 2 ROP^2,3. However, some ROP eyes have special manifestations in clinical practices, although they have not reached the level of type 1 ROP, manifested as gradually thickened or widened ridges without typical manifestation of plus disease, or no regression of the retinal lesions for a long time of follow-up. This kind of ROP is more serious than type 2 ROP, and it is difficult to decide whether to continuous follow-up or give treatment. These non-type 1 ROP eyes may be recommended for treatment to avoid unnecessary medical disputes or irreversible vision damage caused by the aggravation of the disease.

Previous studies have reported that 9-27% affected eyes of patients with non-Type 1 ROP receive treatment in different countries ^4-7. In recent years, intravitreal injection of anti-VEGF drugs for the treatment of ROP, with advantages of simple operation, minimal invasion and continuous growing of retinal vessels to the periphery after injection, has gradually become an important treatment method^8-10. There is a lack of relevant research on the treatment of intravitreal injection of anti-VEGF drugs for non-type 1 ROP in critical conditions. In this study, non-type 1 ROP cases who had received intravitreal injection of anti-VEGF drugs in our hospital were enrolled to analyze the treatment effect, clinical characteristics, and treatment reasons and to explore the personalized diagnosis and treatment for ROP with special clinical characteristics.

Methods

Subjects and data

This was a retrospective study. ROP infants who had received intravitreal injection of anti-VEGF drugs were collected in the Department of Ophthalmology of Henan People's Hospital (Henan Eye Hospital) from September 2018 to June 2021, of whom, type 1 and non-type 1 ROP cases were sub-grouped. This study was conducted with the approval of the Medical Ethics Committee of Henan Eye Hospital (Approval Number HNEECKY-2021 (49)) and performed in accordance with the Declaration of Helsinki. All methods were confirmed to be performed with relevant regulations. All infant’s parents or legal guardians signed the written informed consent prior to treatment.

Inclusion and exclusion criteria

Diagnostic criteria for type 1 ROP were as follows ²: (1) ROP at stages 1-3 with plus in zone I; and ROP at stage 3 without plus in zone I (2) stage 2 or 3 ROP with plus in zone II; (3) aggressive ROP (A-ROP). Those who did not meet any above conditions and received intravitreal injection of anti-VEGF drugs were defined as non-type 1 ROP. Infants with unstable vital signs caused by systemic diseases in heart, brain, lung or accompanied by other fundus lesions were excluded. 

Study selection

The retinal examination of ROP infants was performed in the neonatal intensive care unit (NICU) and ophthalmic clinic by two experienced doctors under topical anesthesia after mydriasis with RetCam 3. All abnormal retinal images were judged by a senior pediatric retinal professor (Haitao Zhang MD, associated professor), then diagnosis and treatment suggestions were made. Information of name, gender, gestational age(GA), birth weight(BW), and the time of examination and injection was recorded after the retinal examination. The zone, stage, range, and plus disease of binocular retinal lesions were recorded according to ICROP3 ¹¹.

Anti-VEGF drugs used in the study were ranibizumab (0.25mg/0.025ml), conbercept (0.25mg/0.025ml), and aflibercept (1mg/0.025ml). The latter two drugs were fusion proteins. Intravitreal injection for ROP was performed under topical anesthesia. After local disinfection, a 29G needle-equipped syringe was used to penetrate the eyeball wall at 1.0-1.5 mm posterior of the limbus to the vitreous cavity parallel to the optical axis. Antibiotic eye drops were used for 3-5 days to prevent ocular infection and the first eye review was conducted within 7 days. The interval of the next review (1-3 weeks) should be determined according to the retinal manifestations, and patients should be followed up until complete retinal vascularization or for at least 24 weeks.

The characteristics of included subjects were analyzed according to the number of cases. The grouping criteria were as follows: ROP cases were included in the type 1 ROP group if both eyes met the above criteria and received intravitreal injection of anti-VEGF drugs, or one eye met the criteria and received intravitreal injection while the contralateral eye with mild lesions did not receive treatment. ROP infants whose one eye or both eyes did not meet the criteria of type 1 ROP and received intravitreal injection were included in the non-type 1 ROP group. The curative effect, retinal pathological characteristics, and causes for the treatment of non-type 1 ROP were analyzed according to the number of eyes. The characteristics of included subjects were analyzed according to the number of cases.

Quality Assessment

The treatment effect was evaluated as follows: (1) Cured, complete retinal vascularization. Retinal vessels gradually grew to the ora serrata or less than 1 PD (Papillary Diameter) away from the ora serrata around zone III; (2) Improved, the retina was not completely vascularized. The retinal vessels had reached zone III, and there were still non-vascular areas, but without obvious active lesions at the last follow-up. (3) Recurrence. The tortuous dilation of retinal vessels was relived and the ridge became flattened in the early stage after the operation, but then the tortuous dilation of vessels, ridge aggravation, and neovascularization occurred again in the retina. (4) Aggravation. The tortuous dilation of retinal vessels was not significantly reduced, and the proliferation and traction were aggravated, even leading to retinal detachment. The improved cases still required regular examination. The recurrent cases were treated with intravitreal injection of anti-VEGF drugs again or retinal laser photocoagulation. The aggravating cases were treated with laser photocoagulation according to the retinal manifestations or surgery in case of retinal detachment.

The reasons for the treatment of non-Type 1 ROP were as follows: (1) pre-plus diseases in the retina, (2) ridge aggravation, shown as more obvious ridges or ridge extension, or locally thickened and widened ridges, with a risk of increased proliferation. (3) simultaneous treatment of the contralateral eye; (4) no regression of lesions in persistent stage 2 or 3 for over PMA(Postmenstrual Age) 44 weeks of follow-up; (5) logistical considerations, follow-up might not be timely due to various reasons (such as living far away, parents’ poor understanding, and epidemic control policy, etc.).

Data analyses

Data analyses were performed using the SPSS19.0 statistical software. The differences in birth gestational age (GA), birth weight (BW), hospitalization days in NICU, first injection time, and follow-up time were compared by t-test, and the differences in gender and drug types were compared by χ² test. The treatment effect was analyzed according to the number of afflicted eyes and compared by χ² test. P<0.05 was considered statistically significant.

Results

Subject characteristics

A total of 138 cases (262 eyes) of ROP, including 124 cases (89.9%) with both eyes and 14 cases (10.1%) with unilateral eyes, were included in the study. There were 99 cases (71.1%) in the type 1 ROP group and 39 cases (28.3%) in the non-type 1 ROP group, including 26 bilateral cases (18.8%) (52 eyes, 19.8%) and 13 unilateral cases (9.4%) (13 eyes, 5.0%). Of unilateral cases, 6 cases (4.3%) had type 1 ROP in one eye and non-type 1 ROP in the contralateral eye.

The characteristics of subjects with non-type 1 ROP and type 1 ROP were shown in Table 1. There was no significant difference in GA, BW, gender proportion, hospitalization days in NICU, and follow-up time between the two groups (P>0.05). While the time of the first treatment of the non-type 1 ROP group was slightly later than that of the type 1 ROP group (39.8±2.7 weeks vs 38.1±2.6 weeks, P<0.01). The difference in the types of anti-VEGF drugs was significant (P<0.05), with a higher proportion of fusion protein drugs in the non-type 1 ROP group (87.2%) than that in the type 1 ROP group (54.5%).

Table 1. Characteristics of subjects with type 1 and non-type 1 ROP (N=138).

^α GA gestational age; BW birth weight.

^β Difference of gender was analyzed by χ² test and the remaining parameters were tested using t-test

Effect assessment

According to the number of eyes (n=262), 65 eyes (24.8%) were non-type 1 ROP. After treatment,27 eyes (41.5%) were cured and 38 eyes (58.5%) were improved. There was no recurrence and aggravation. There were 197 eyes of type 1 ROP. After treatment, 79 eyes were cured (40.1%),100 eyes were improved (50.8%), and 18 eyes recurred (9.1%), without aggravation cases. The difference in treatment effects between the two groups was significant (P<0.05，Table 2). All 18 recurrent eyes in the type 1 ROP group received intravitreal injection of the same anti-VEGF drugs and then the retinal conditions improved.

Table 2. Comparison of effects for eyes with type 1 and non-type 1 ROP after intravitreal injection of anti-VEGF drugs (N=262).

Reasons for the treatment

Of all treated eyes with non-type 1 ROP (n=65) (Table 3), 63 eyes (96.9%) had ROP lesions in zone II, of which there were 5 eyes (3.1%) in posterior zone II, and 2 eyes (3.1%) with ROP in zone Ⅰ. In terms of stage, there were more lesions in stages 2 and 3, with 40 eyes (61.5%) and 23 eyes (35.4%) respectively. In terms of plus diseases, 58 eyes (89.2%) showed pre-plus. As for treatment reasons, the main reason was pre-plus in 58 eyes (89.2%), followed by ridge aggravation in 22 eyes (33.8%), simultaneous treatment in 9 eyes (13.8%) due to contralateral eye treatment, no regression of lesions in stage 2 or 3 for over PMA 44 weeks of follow-up in 8 eyes (12.3%), and logistical considerations in 4 eyes (6.2%). The above reasons could exist simultaneously (Figure 1). The preoperative features and specific reasons for treated non-type 1 ROP cases are shown in Table 4.

Table 3. Characteristics of pathological manifestation of non-Type 1 ROP receiving treatment.

^α± referred to pre-plus diseases.

Table 4. List of non-type 1 ROP cases received intravitreal injection of anti-VEGF drugs (N =39)

^α II referred to periphery zone Ⅱ.

^β ± referred to pre-plus.

^γ R,C and A were abbreviations for ranibizumab, conbercept, aflibercept. NA referred to untreated.

^δOne eye of type 1 ROP and the contralateral eye of non-type 1 ROP in 6 cases (ID. 10,12,15,34,38,39). One eye of non-type 1 ROP and contralateral eye untreated in 7cases (ID.13,16,19,20,27,30,35).

Discussion

Some previous studies analyzed the treatment reasons of non-Type 1 ROP (seen in Table 5)^4,6,12,17, but the main treatment method in these studies was laser photocoagulation. No literature had not been retrieved to explore the effect of intravitreal injection of anti-VEGF drugs on the treatment of non-type 1 ROP currently. Laser photocoagulation and anti-VEGF therapy are the main options for ROP currently. Laser therapy led to permanent destruction of the peripheral retina, and peripheral retinal vessels continued to develop after anti-VEGF agents treatment¹⁵. As to efficacy compared to laser therapy, anti-VEGF agents as primary treatments had potential advantages for eyes with posterior ROP(zone I type 1 ROP and A-ROP), and for eyes with zone II type 1 ROP, anti-VEGF agents therapy showed similar efficacy, however, was significantly higher rate of reactivation¹⁸. Laser treated eyes had greater trend to myopia and astigmatism than anti-VEGF thrapy^18,19. For the above reasons, anti-VEGF therapy performed under topical anesthesia was preferred for treatment with ROP during our clinical practice, and laser therapy was used option for ROP with the risk of obvious fibrosis or the recurrent eyes. In addition, laser coagulation for ROP needed to be operated under general anesthesia which most parents of neonates were reluctant to choose in China.

Of the 263 eyes treated in this study, 65 eyes (24.8%) were non-type 1 ROP, showing a higher proportion than that in previous studies (9.5-13.7%)^4,6,12. Because that the treatment for ROP cases in this study was intravitreal injection of anti-VEGF drugs, which are simpler operated and more minimally invasive than laser therapy¹⁵. In this study, lesions in all eyes with non-type 1 ROP were relieved after treatment, which was similar to the results of previous studies ¹². It was also found that the treatment effect of non-type 1 ROP eyes was better than that of type 1 ROP eyes, which may mainly be related to the milder condition. In this study, the proportion of fusion protein drugs used was higher in the non-type 1 ROP group (87.2%) than that in the type 1 ROP group (54.5%). This might be other potential reason for the difference in treatment effects between the two groups. Some retrospective studies found that the recurrence rate of ROP eyes treated with fusion protein drugs (conbercept or aflibercept) was lower than that of ROP eyes treated with ranibizumab ^13,14. But a multicentral prospective trial to compare of clinical outcomes of conbercept vs ranibizumab treatment for ROP found there was no significant statistical difference in the recurrence rate between the two anti-VEGF agents²⁰. It is still controversial whether there is difference between the efficacy of ranibizumab and fusion protein drugs in the treatment of ROP. The different proportion of drug selection in our study was associated with the time to market in China.  

Table 5. Previous studies of non-type 1 ROP treatment.

^αIVR: intravitreal injection of bevacizumab.

^βReasons of treatment were arranged in descending order of proportion.

Of eyes with non-type 1 ROP treated in this study, 63 cases (96.9%) had more lesions in zone II, and 40 eyes (61.5%) and 23 eyes (35.4%) had more lesions in stages 2 and 3, respectively. The characteristics of pathological manifestation were similar to those of the finding of Gupta MP et al ⁴, in which, 11 eyes (84.6%) had lesions in zone II, and 12 eyes (92.3%) had lesions in stages 2 and 3. While in the study of Liu T et al⁶, most eyes (66%) had pre-plus lesions in zone II stage 3. The above evidence suggests that ROP should be checked carefully about the changes of lesions at stage 2 or 3 in zone II.

The main treatment reason for non-type 1 ROP eyes in this study was the pre-plus disease (89.2%), which was different from previous studies^4,6,12. In the study of Gupta MP et al and Rajan RP et al, the most important treatment reason was structural changes in the fundus caused by the traction of the ridge (69.2% and 72.7%, respectively)^4,12. Pre-plus disease (33.3%) was the second reason in the study of Rajan RP et al¹². The major reason in Liu et al’s study was the contralateral eye with type 1 ROP (43%), followed by stage 3 ROP with pre-plus (30%)⁶. As for pre-plus and plus disease, ICROP3 defined it as a continuous spectrum of retinal vascular changes from normal, to pre-plus, and finally to plus disease. Consistent judgments of different scholars only in the normal and last plus stages¹¹. This suggests a high possibility of clinical disagreement over pre-plus lesions, resulting in no typical plus lesions in some ROP eyes and further risk of retinal traction with progressive worsening of the ridge. Due to the use of anti-VEGF drugs, we paid more attention to the judgment of pre-plus in the ROP examination.

The second cause of treatment in this study was ridge aggravation (33.8%), shown as more obvious or/and more extension, or thickened and widened locally. Actually, the ridge aggravation was often accompanied by pre-plus (Fig. 1). Koucheki R et al confirmed that pre-plus was significantly correlated with increased ridges (≥2 continuous clock hours of persistent stage 3 crossing the temporal horizontal midline) in the eyes with stage-3 ROP persisting ≥40 weeks of PMA¹⁷. The ridge aggravation in this study were slightly milder than the structural changes such as macular traction, retinal traction, or folds produced due to the tangential traction caused by the straightening of the temporal vessels in the fundus mentioned in previous studies^4,6,12. Under these fibrosis conditions, intravitreal injection of anti-VEGF drugs may not be recommended because of the risk of aggravated traction^21,22. 

In this study, the simultaneous treatment of contralateral eyes accounted for 13.8%. Most previous studies considered that acute ROP commonly occurs in both eyes. For example, 79.1% of ROP infants have high-risk pre-threshold disease in both eyes at the time of enrollment in an ETROP study². A study on Telemedicine Approaches to Evaluating of Acute-Phase Retinopathy of Prematurity (e-ROP) found that 72.7% of infants had the same severity of ROP in both eyes among ROP image sessions¹⁶.

However, our study does not recommend arbitrary early treatment for non-type 1 ROP. Previous studies suggested that ROP with stage 3 can be treated when no regression is found after 41 weeks of PMA⁴ or continuous 6 weeks of follow-up^6,12. In this study, the average time of the first treatment for eyes with type 1 ROP was 38.1 weeks, while the follow-up of another 6 weeks was 44 weeks for non-type I ROP eyes with some of the above particular retinal features. Meanwhile, due to the use of anti-VEGF drugs, in order to avoid obvious fibrosis, we paid more attention to the progression of lesions at stage 2 and stage 3. Therefore, our study considered a treatment for ROP infants with lesions at persistent stages 2 and 3 without regression at PMA 44 weeks or more, and whether there were other retinal manifestations was also taken into consideration. In this study, 4 cases (8 eyes) (12.3%) were followed up for ≥ PMA 44 weeks and then received anti-VEGF treatment, and the fundus was simultaneously with pre-plus lesions or ridge aggravation or logistical considerations before treatment. During the struggling follow-up period, more attention should be paid to the changes of extraretinal neovascular proliferation, and anti-VEGF therapy should be performed in time before the fibrosis is obvious. Once obvious fibrosis has formed, laser coagulation will be recommended, because retinal traction may be aggravated after anti-VEGF treatment^21,22.Unlike other ocular neovascular conditions(e.g. wetAMD) in which VEGF is continual released, there is a single burst of VEGF that promotes neovascularization in ROP²³. The delayed anti-VEGF therapy given at a period when VEGF levels are decreasing may promote fibrosis driven by transforming growth factor-β(TGF-β) and connective tissue growth factor(CTGF)^24-26.Traction from fibrosis may cause retinal detachments. 

In this study, 4 eyes (6.2%)2 cases (NO.4 and 5，Table 4) were treated for the logistical considerations, that was, follow-up might not be timely due to various reasons. Their parents lived far away or affected by epidemic control reasons (all eyes accompanied by other reasons, such as pre-plus or follow-up time ≥ PMA44w), and might not be followed up in time, and treatment was chosen considering that the retinal lesions tended to aggravate at the same time. The logistical considerations of Liu T et al ’s study was the difficulty in follow-up or general anesthesia for non-ROP surgery (3%)⁶. The intravitreal injections for ROP infants in our study were performed under topical anesthesia and there was no treatment under general anesthesia due to other diseases. For some ROP cases with difficulty in follow-up, detailed communication with the parents before treatment was recommended to emphasize the importance of follow-up, especially after anti-VEGF drug treatment that requires longer follow-up. In fact, the 2 cases were followed up in our hospital within 4 weeks after treatment. Then the following examinations from the 6th week was started in the local hospital and the regular examination results including some retinal images would be transmitted to our research group through WeChat or the network of telemedicine.

Our study had some limitations. First, to avoid medical disputes caused by delayed treatment during clinical practice, there was no control group set. So, it was unable to accurately judge the progression of non-type 1 ROP with aggravating tendency if not treated. The sample in the study group will gradually be increased to collect and follow up carefully some untreated cases with non-type 1 ROP so as to investigate reasonable methods in the future. Secondly, as for the systemic effect of anti-VEGF drugs on premature infants, previous studies have confirmed that the intravitreal injection of anti-VEGF drugs in ROP eyes has a certain inhibitory effect on the level of VEGF in blood^27-30. But different anti-VEGF drugs have different effects. There were no differences in plasma free VEGF concentrations of ROP infants after bilateral intravitreal injection of ranibizumab from RAINBOW Trial³¹. Cheng Y et al found that the serum VEGF levels in ROP infants were suppressed for a short time after intravitreal injection of conbercept, and returned to the preoperative level at 4 weeks²⁹.Huang CY found that serum VEGF levels in type 1 ROP infants were suppressed for 3 months after treatment with aflibercept or bevacizumab, but the suppression of systemic VEGF was more pronounced in infants treated with bevacizumab than those treated with aflibercept³⁰. The suppression of VEGF in blood may affect the development of important organs of premature infants. Considering these potential risks, we are very cautious in the treatment of ROP and do not arbitrarily expand the treatment indications. In clinical practice, we always follow the professional guidelines and recommendations. Type 1 ROP eyes need treatment, while type 2 ROP eyes need close observation. However, whether continuous observation or treatment of ROP infants with aggravating tendency but not reaching the typical fundus manifestations of type 1 was confused and should be discussed carefully. At the meanwhile, we have explored a lower dose of anti-VEGF drug intravitreal injection for ROP to reduce the possible systemic adverse reactions (published in Chinses, http://www.coretina.com/article/10.3760/cma.j.cn511434-20200219-00066). 

Conclusions

Non-type 1 ROP with some characteristics, such as pre-plus, ridge aggravation, treatment with contralateral eyes, no regression in persistent stage 2 or 3 for follow-up ≥PMA 44 weeks, and logistical considerations, can be considered carefully to be received intravitreal injection of anti-VEGF drugs based on current expert consensus or guidelines.

Declarations

Acknowledgements 

Funded by Project of Henan Science and Technology Development Plan (182102311209).

Particularly grateful to Ms. Yingying Xu. As a nurse in the operating room of Henan Eye Hospital, she supplied the meticulous nursing supports of intravitreal injections for ROP. 

Competing interests

The authors declare no competing interests.

Data Availability

The data used to support the findings of this study are available from the corresponding author upon request.

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