The aim of this study was to investigate the necessity of early intraocular pressure measurement after intravitreal injection.

From July 22 to August 31, 2021, 1018 consecutive patients (1193 eyes) who underwent intravitreal injection in Beijing Tongren Eye Center, Beijing Tongren Hospital Affiliated to Capital Medical University were collected. Among them, there were 506 male (597 eyes) and 512 female (596 eyes) with an average age of (60.2±13.9) years-old (ranged from 9 to 99 years-old). The gender, age, eye type, IOP, disease type and injected drugs of all patients were recorded. The intraocular pressure (IOP) before and after injection injection were measured. The data of age and IOP were expressed as ±s. The overall number of eyes and the number of eyes of different diseases in each IOP segment are expressed in descriptive statistics and percentage. The difference of IOP before and after injection were used to compared by paired t test.

After intravitreal injection for 30 mins, the IOP of 1183 eyes (99.16%) was less than or equal to 25 mmHg (1 mmHg=0.133 kPa). Among them, there were 556 eyes (47.00%) with diabetic retinopathy (DR), 304 eyes (25.70%) with wet age-related macular degeneration (AMD), 35 eyes (2.96%) with other choroidal neovascularization (CNV), 247 eyes (22.81%) with retinal vein occlusion (RVO), 15 eyes (1.39%) with neovascular glaucoma (NVG), and 26 eyes (2.20%) with other diseases. There were only 10 eyes with IOP over 25 mmHg, of which IOP of 3 eyes with 26 to 30 mmHg, 6 eyes with 31 to 40 mmHg, and 1 eye with over 40 mmHg. There were one eye with RVO, one eye with DR, 2 eyes with AMD, 6 eyes with NVG. The IOP was (43.67±8.71)mmHg in 6 eyes with NVG before injection. There was IOP of 1 eye more than 40 mmHg after injection for 30 mins and IOP decreased to 40 mmHg after using IOP reducing drugs. IOP of 5 NVG eyes was 26~40 mmHg after injection for 30 mins. After observation for half an hour or 1 hour, the IOP of 4 eyes with non-NVG decreased to less than 25mmHg. For ranibizumab, conbercept injection, the IOP before injection were (15.51±4.71)mmHg and (15.03±3.79)mmHg, respectively. The IOP after injection for 30 mins was (17.00±4.81)mmHg and (16.62±4.14)mmHg, respectively. There were significant differences in IOP between pre-injection and post-injection between groups by paired ttest (t=-5.551, - 6.187; P< 0.05). The IOP of Ozurdex injection group before and after injection was (14.80±2.59)mmHg, (14.80±2.59)mmHg, respectively. There was no significant difference between groups (t=0.279, P>0.05). There were 21 eyes, 18 eyes and 2 eyes in the aflibercept, Ozurdex combined with ranibizumab and Ozurdex combined with combercept groups, respectively. The preoperative IOP were (14.95±2.56)mmHg, (14.44±2.30)mmHg and (16.00±2.83)mmHg, respectively; the postoperative IOP were (17.04±3.46)mmHg, (14.11±4.96)mmHg and (16.50±0.71)mmHg, respectively. Preoperative and postoperative IOP of 21 eyes with NVG were (37.76±6.97)mmHg, (22.00±8.77)mmHg , respectively with significant difference between them by paired ttest (t=6.447, P<0.05). Preoperative and postoperative IOP of 14 eyes (66.67%) with proliferative DR were (38.00±12.92)mmHg, (25.07±11.64)mmHg, respectively. Preoperative and postoperative IOP of 7 eyes (33.33%) with CRVO were (37.29±4.82)mmHg, (15.00±5.89)mmHg, respectively. Preoperative and postoperative IOP of 16 eyes (76.19%) injected with ranibizumab were (37.56±7.95)mmHg, (23.00±12.20)mmHg, respectively. Preoperative and postoperative IOP of 5 eyes (76.19%) injected with conbercept were (38.40±2.30)mmHg, (18.00±5.43)mmHg

The probability of IOP higher than that after routine intravitreal injection for 30 mins is very low, thus it is unnecessary to measure IOP after intravitreal injection. For patients with glaucoma, such as glaucoma with NVG, IOP can be measured after injection.