Quantitative assessment of radial peripapillary capillary plexus vessel density after retrobulbar block in cataract surgery: a randomized controlled trial

Abstract

Purpose

To evaluate the effect of retrobulbar anesthesia administered before phacoemulsification on radial peripapillary capillary (RPC) plexus vessel density (VD) using optical coherence tomography angiography (OCTA).

Methods

In this prospective randomized comparative study, 72 consecutive patients undergoing phacoemulsification were randomly assigned to topical anesthesia (n = 36) or retrobulbar anesthesia (n = 36). OCTA imaging was performed preoperatively and repeated at postoperative week 1 and month 1. En face OCTA scans centered on the optic nerve head (4.5 × 4.5 mm) were used to quantify RPC plexus VD automatically using AngioAnalytics™ software. The primary outcome was change in RPC VD over time. Between-group and longitudinal comparisons were performed, including repeated-measures analysis to evaluate group-by-time interactions.

Results

No significant changes in RPC plexus VD were observed within either group at postoperative week 1 or month 1 compared with baseline (all p > 0.05). Likewise, no significant differences were detected between the topical and retrobulbar anesthesia groups at any evaluated time point or in the magnitude of VD change from baseline to month 1 (all p > 0.05). Effect size analyses demonstrated only small between-group differences, and all corresponding 95% confidence intervals included zero. Repeated-measures analysis revealed no significant group-by-time interaction for any RPC VD parameter (all p > 0.05).

Conclusion

Retrobulbar anesthesia was not associated with detectable persistent changes in RPC plexus VD at postoperative week 1 or month 1 after uncomplicated phacoemulsification. No clinically meaningful differences in RPC VD were observed between retrobulbar and topical anesthesia. Further studies incorporating earlier postoperative OCTA assessments are warranted to evaluate potential transient vascular effects.

Trial registration

ISRCTN Registry, ISRCTN13084070. Registered on 26 June 2026; retrospectively registered.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s12886-026-05324-4.

Introduction

Phacoemulsification is currently the most common treatment for cataract surgery, and various anesthesia techniques are used during the procedure [1] Topical anesthesia is the most frequently preferred method due to the sufficient comfort it provides during the relatively short surgery time and its favorable safety profile [1] Other anesthesia options include subconjunctival, sub-Tenon’s, intracameral, peribulbar, retrobulbar, and general anesthesia [2].

Retrobulbar block provides anesthesia to the conjunctiva, cornea, sclera, and uveal tissues by inhibiting the ciliary nerves, while causing ocular akinesia by blocking cranial nerves III, IV, and VI. [3] Although more effective than other regional anesthesia techniques, it is more invasive and carries a higher risk of complications, including rare permanent vision loss [4] One of the serious complications associated with retrobulbar injection is optic neuropathy [3] The current literature on this complication lacks large series or prospective randomized studies. Therefore, its true incidence and underlying pathophysiological mechanisms are not fully understood. Mechanical damage to the optic nerve, anesthesia-induced neurotoxicity, vasoconstriction, and ischemic damage are among the proposed mechanisms [3, 5, 6] Experimental evidence has been reported showing that local anesthetic agents can increase perineurial permeability, leading to endoneurial edema, Schwann cell damage, axonal degeneration, and Wallerian degeneration [7] Furthermore, electrophysiological reports have indicated that these agents can affect the electrical activity of the optic nerve [8].

There are also studies that retrobulbar anesthesia affects ocular blood flow [5, 6, 9] However, these are generally case series and studies evaluating parameters that are likely to be affected by systemic factors. Findings of these studies support the possibility of transient retrobulbar anesthesia-related alterations in ocular perfusion, these approaches do not directly quantify the microvascular network of the optic nerve head. Consequently, whether retrobulbar anesthesia produces detectable changes in peripapillary microvascular density remains unclear.

Optical coherence tomography angiography (OCTA) allows for the quantitative assessment of the microvascular structure of the optic nerve head, including the radial peripapillary capillary (RPC) plexus [10] The RPC plexus contributes to the vascular supply of the retinal nerve fiber layer and has been shown to exhibit measurable alterations in several optic nerve and retinal disorders [11, 12] Therefore, OCTA-based assessment of RPC vessel density (VD) may provide a useful approach for investigating potential microvascular effects of retrobulbar anesthesia that cannot be directly characterized using conventional structural or Doppler-based techniques. To the best of our knowledge, searches of PubMed/MEDLINE, Scopus, and Web of Science (last updated 19 August 2026) identified no previous OCTA studies evaluating optic nerve head microvascularity following retrobulbar anesthesia. This represents an important knowledge gap, particularly because vascular compromise has been proposed as one of the mechanisms underlying retrobulbar anesthesia-associated optic neuropathy.

Therefore, the present randomized controlled trial aimed to evaluate longitudinal changes in RPC plexus VD before and after phacoemulsification in patients receiving retrobulbar anesthesia and to compare these changes with those observed in patients receiving topical anesthesia. We hypothesized that if retrobulbar anesthesia exerted a persistent microvascular effect on the optic nerve head, postoperative RPC plexus VD would differ from baseline and/or from that observed in the topical anesthesia group.

Methods

Study population and ethical procedures

This prospective, randomized, two-group, parallel comparative study included 72 patients (72 eyes) scheduled for cataract surgery at the Ophthalmology Clinic of Gulhane Training and Research Hospital, with participants allocated in a 1:1 ratio to topical or retrobulbar anesthesia. The study adhered to the principles of the Declaration of Helsinki at every stage. The study was approved by the University of Health Sciences Scientific Research Ethics Committee (approval no. 2025 − 578) on 23 December 2025. Patient recruitment commenced on 26 December 2025. The final participant was enrolled on 7 February 2026, and study follow-up was completed on 7 March 2026. The study was prospectively designed, with participant enrollment, randomization, and data collection conducted according to the predefined study protocol. However, registration in a public clinical trial registry was completed after the initiation of participant enrollment; therefore, the trial was retrospectively registered with the ISRCTN Registry (ISRCTN13084070) on 26 June 2026. No important changes were made to the study methods after trial commencement. Both topical and retrobulbar anesthesia were routinely used anesthetic techniques at our institution during the study period, and no participant received an intervention outside standard clinical practice. All patients participating in the study were provided with the necessary information about cataract surgery and anesthesia techniques, and written informed consent was obtained from all patients.

Ophthalmological assessment and surgical procedure

All patients underwent standard ophthalmic evaluation one week before surgery and at 1 week and 1-month post-surgery. These examinations included determining the best corrected visual acuity (BCVA), measuring intraocular pressure (IOP) with applanation tonometry, and evaluating the anterior and posterior segments with a slit lamp. Eligible participants were adults aged 50 years or older with visually significant age-related cataract scheduled for elective phacoemulsification, who were able to provide written informed consent and undergo OCTA imaging of adequate quality. Individuals with ocular comorbidities and systemic vascular diseases that could affect the measurement of quantitative parameters in OCTA scans were excluded from the study. Exclusion criteria included previous ocular trauma, corneal ectatic diseases, media opacities affecting image quality, retinal vascular disease, high or degenerative myopia, age-related macular degeneration, glaucomatous or non-glaucomatous optic neuropathy, and a history of intraocular surgery. Cataract extraction was carried out using a phacoemulsification technique via a 2.65-mm clear corneal incision. In every case, a single-piece monofocal intraocular lens (Acriva UD 613; VSY Biotechnology, Amsterdam, Netherlands) was implanted in the capsular bag. Total surgical duration and cumulative dissipated energy (CDE) measurements were also recorded for each patient.

Anesthesia protocols

Patients were assigned to the topical anesthesia or retrobulbar anesthesia groups using block randomization with a fixed block size of four and a 1:1 allocation ratio. Within each block, two participants were assigned to each anesthesia group, and the allocation sequence was randomized using computer-generated random numbers created with the RAND() function in Microsoft Excel (Microsoft Corp., Redmond, WA, USA). The randomization sequence was generated before participant enrollment by an independent investigator who was not involved in participant recruitment, clinical assessment, image analysis, or statistical evaluation. The allocation sequence was kept exclusively by this independent investigator and was not accessible to the investigators responsible for participant recruitment or clinical assessment. Eligible participants were enrolled by the clinical investigators without knowledge of the upcoming allocation. After enrollment, the independent investigator disclosed the corresponding group assignment according to the predefined randomization sequence. A total of 36 patients were allocated to each anesthesia group. For topical anesthesia, 0.5% proparacaine hydrochloride ophthalmic drops (Alcaine; Alcon, Fort Worth, TX, USA) were used immediately before surgery. For retrobulbar anesthesia, patients were positioned supine with the head aligned neutrally. A 22-gauge needle measuring 0.70 × 38 mm was introduced transcutaneously at the inferotemporal orbital margin. The needle was advanced posteriorly beyond the globe’s equator and subsequently redirected superonasally toward the orbital apex. After confirming absence of intravascular placement by aspiration, 4 mL of a local anesthetic mixture containing 40 mg/2 ml lidocaine and 0.025 mg/2 ml epinephrine was slowly injected. To increase the effectiveness of the procedure and ensure standardization for each patient, needle placement and injection were performed under ultrasound guidance.

Optical coherence tomography angiography

Optical coherence tomography angiography scans were performed preoperatively (one week before surgery) using an RTVue XR Avanti OCTA device (Optovue, Inc., Fremont, CA, USA) and repeated at week 1 and month 1 postoperatively. All OCTA examinations were performed after pharmacological pupil dilation using topical tropicamide (Tropamid^®, 0.5% tropicamide ophthalmic solution; Bilim Pharmaceuticals, Turkey) to ensure optimal image acquisition and image quality. To minimize the impact of motion and quality-related artifacts, images with a signal strength index exceeding 55 were considered suitable for quantitative analysis. AngioVue optic disc scanning protocol with a 4.5 × 4.5 mm imaging field was used. The vitreous, optic nerve head, RPC plexus, and choroid were automatically segmented. The RPC plexus, extending 100 μm below the internal limiting membrane, was subjected to quantitative evaluation [11] The instrument’s proprietary AngioAnalytics software was used to automatically generate VD values. Quantitative parameters were obtained for the whole image, inside disc and peripapillary sectors (including superior and inferior hemifields). Prior to statistical analysis, two qualified experts independently reviewed each OCTA image to ensure accurate segmentation and adequate image quality. Both graders were masked to the anesthesia group assignments and clinical information of the participants. Because the two anesthesia techniques were procedurally distinct, the operating surgeon could not be masked to treatment allocation.

Outcomes

The prespecified primary outcome was RPC plexus VD measured by OCTA at baseline, postoperative week 1, and postoperative month 1. No key secondary outcome measure was designated in the trial registry. Postoperative BCVA, IOP, surgical duration, CDE, and intraoperative and postoperative complications were evaluated as additional clinical and surgical variables. No changes were made to the prespecified outcome measures after trial commencement.

Statistical analysis

The distribution of continuous measures was evaluated using the Shapiro-Wilk and skewness-kurtosis tests, and since the measures showed a normal distribution, parametric methods were used. Descriptive data for continuous variables were presented as mean ± standard deviation, and for categorical variables as number (n) and percentage (%). Comparison of continuous variables between groups was performed using the independent samples t-test. Repeated measures ANOVA was used for within-group comparisons between different time points. When significant differences were detected as a result of this analysis, Bonferroni post-hoc analysis was performed to determine the parameters causing the differences. Relationships between categorical variables were analyzed using the chi-square test. A p-value < 0.05 was considered statistically significant. Statistical analyses were performed using SPSS software (version 26.0; IBM Corp., Armonk, NY, USA). In addition to p values, effect sizes and 95% confidence intervals (CI) were calculated for the principal between-group comparisons. Cohen’s d was used to quantify the magnitude of between-group differences and was interpreted according to conventional thresholds (0.2, small; 0.5, moderate; and 0.8, large effect). Mean differences with corresponding 95% CI were reported to provide estimates of the magnitude and precision of the observed effects. A repeated-measures analysis of variance including time, group, and group-by-time interaction effects was performed to determine whether longitudinal changes in RPC VD differed between the two anesthesia groups. No formal a priori sample size calculation was performed. The sample size was based on the number of eligible consecutive patients enrolled during the study period, with participants allocated to the two anesthesia groups in a 1:1 ratio.

Results

A total of 72 eyes from 72 patients were included in the study, with 36 eyes assigned to the topical anesthesia group and 36 eyes to the retrobulbar anesthesia group. All 72 randomized participants (36 in each group) were included in the analyses according to their originally assigned anesthesia group. No participants were lost to follow-up or excluded after randomization. Baseline demographic and clinical characteristics were comparable between groups, including age (71.1 ± 8.5 vs. 71.2 ± 8.1 years, p = 0.96), sex distribution (p = 0.83), BCVA, axial length, refractive status, surgical duration, and CDE (all p > 0.05) (Table 1). Postoperative IOP and BCVA outcomes were comparable between the two groups throughout follow-up (all p > 0.05). No intraoperative or postoperative complications, including clinically detected macular edema, were observed in either group during follow-up. The trial was completed as planned and was not terminated early. Regarding the primary study outcome, RPC plexus VD measurements showed no significant changes from baseline to postoperative week 1 or month 1 in either anesthesia group (Table 2; all p > 0.05). Likewise, no significant between-group differences were observed in any RPC sector at any evaluated time point or in the magnitude of change from baseline to postoperative month 1 (Table 3; all p > 0.05). Effect size analyses demonstrated uniformly small between-group differences (all Cohen’s d < 0.30), and all corresponding 95% CI included zero. Repeated-measures analysis demonstrated no significant group-by-time interaction for any RPC VD parameter (all p > 0.05).

Table 1.

Demographic characteristics and key clinical parameters of the study population

	Topical anesthesia (n = 36)	Retrobulbar anesthesia (n = 36)	p
Age (years)	71.1 ± 8.5	71.2 ± 8.1	0.96
Male, n (%)	18 (50)	17 (47.2)	0.83
BCVA (logMAR)	0.45 ± 0.11	0.48 ± 0.13	0.29
Axial length (mm)	23.11 ± 1.3	23.54 ± 1.6	0.21
Refractive status (D)	-1.52 ± 1.06	-1.68 ± 1.22	0.55
Surgical duration (minutes)	13.5 ± 3.3	13.7 ± 2.9	0.79
CDE (%-seconds)	5.1 ± 2.3	5.2 ± 2.7	0.87

Parameters were expressed as numbers, percentages, and mean ± standard deviation

BCVA, best-corrected visual acuity; logMAR, logarithm of the minimum angle of resolution; mm, milimeter; D, diopter; CDE, cumulative dissipated energy

Table 2.

The change in the vessel density of the radial peripapillary capillary plexus in two anesthesia groups

Type of anesthesia	RPC Density (%)	Preoperative	Postoperative week one	Postoperative month one	p*
Retrobulbar anesthesia (36 eyes)	Whole image	48.87 ± 1.86	48.78 ± 2.24	48.84 ± 2.49	0.62
	Inside disc	48.89 ± 2.65	48.61 ± 2.85	48.59 ± 2.91	0.45
	Peripapillary	51.19 ± 2.62	51.01 ± 3.08	50.93 ± 2.90	0.53
	Superior-Hemi	50.90 ± 2.65	50.76 ± 2.94	50.67 ± 2.93	0.35
	Inferior-Hemi	51.00 ± 3.61	50.85 ± 3.93	50.75 ± 3.79	0.44
Topical anesthesia (36 eyes)	Whole image	48.63 ± 2.22	48.46 ± 2.37	48.31 ± 2.21	0.71
	Inside disc	48.12 ± 4.41	47.88 ± 4.56	47.85 ± 4.58	0.87
	Peripapillary	50.28 ± 3.64	50.06 ± 3.68	49.92 ± 4.05	0.41
	Superior-Hemi	50.17 ± 3.56	49.87 ± 3.68	49.86 ± 3.63	0.54
	Inferior-Hemi	50.17 ± 3.59	49.89 ± 3.60	49.86 ± 3.47	0.57

RPC, radial peripapillary capillary. Parameters were expressed as mean ± standard deviation

* Repeated-measures ANOVA

Table 3.

Comparison of the radial peripapillary capillary plexus vessel density measurements between two anesthesia groups

RPC Density (%)	Retrobulbar anesthesia (36 eyes)	Topical anesthesia (36 eyes)	Mean difference (95% CI)	Cohen’s d	p*
Preoperative
Whole image	48.87 ± 1.86	48.63 ± 2.22	0.24 (-0.72 to 1.20)	0.12	0.77
Inside disc	48.89 ± 2.65	48.12 ± 4.41	0.77 (-1.04 to 2.58)	0.21	0.51
Peripapillary	51.19 ± 2.62	50.28 ± 3.64	0.91 (-0.60 to 2.42)	0.29	0.43
Superior-Hemi	50.90 ± 2.65	50.17 ± 3.56	0.73 (-0.74 to 2.20)	0.23	0.78
Inferior-Hemi	51.00 ± 3.61	50.17 ± 3.59	0.83 (-0.85 to 2.51)	0.23	0.92
Postoperative week one
Whole image	48.78 ± 2.24	48.46 ± 2.37	0.32 (-0.76 to 1.40)	0.14	0.86
Inside disc	48.61 ± 2.85	47.88 ± 4.56	0.73 (-1.09 to 2.55)	0.19	0.83
Peripapillary	51.01 ± 3.08	50.06 ± 3.68	0.95 (-0.66 to 2.56)	0.28	0.58
Superior-Hemi	50.76 ± 2.94	49.87 ± 3.68	0.89 (-0.69 to 2.47)	0.27	0.92
Inferior-Hemi	50.85 ± 3.93	49.89 ± 3.60	0.96 (-0.82 to 2.74)	0.25	0.94
Postoperative month one
Whole image	48.84 ± 2.49	48.31 ± 2.21	0.53 (-0.56 to 1.62)	0.23	0.96
Inside disc	48.59 ± 2.91	47.85 ± 4.58	0.74 (-1.08 to 2.56)	0.19	0.68
Peripapillary	50.93 ± 2.90	49.92 ± 4.05	1.01 (-0.66 to 2.68)	0.29	0.71
Superior-Hemi	50.67 ± 2.93	49.86 ± 3.63	0.81 (-0.75 to 2.37)	0.25	0.54
Inferior-Hemi	50.75 ± 3.79	49.86 ± 3.47	0.89 (-0.81 to 2.59)	0.24	0.61
Change (preop vs. postop month one)
Whole image	0.33 ± 0.78	0.31 ± 0.85	0.02 (-0.36 to 0.40)	0.02	0.25
Inside disc	0.41 ± 0.83	0.39 ± 0.69	0.02 (-0.34 to 0.38)	0.03	0.58
Peripapillary	0.48 ± 0.89	0.44 ± 0.77	0.04 (-0.36 to 0.44)	0.05	0.74
Superior-Hemi	0.51 ± 0.67	0.56 ± 0.71	-0.05 (-0.38 to 0.28)	-0.07	0.33
Inferior-Hemi	0.49 ± 0.75	0.43 ± 0.84	0.06 (-0.32 to 0.44)	0.08	0.28

RPC, radial peripapillary capillary; CI, confidence interval; preop, preoperative; postop, postoperative

* Independent samples t test. Parameters were expressed as mean ± standard deviation. Mean difference was calculated as retrobulbar anesthesia minus topical anesthesia. Cohen’s d represents the standardized mean difference. Change was calculated as preoperative vessel density minus postoperative month 1 vessel density. Values are presented as the mean ± SD of the individual eye-level differences

Repeated-measures ANOVA demonstrated no significant group-by-time interaction for any RPC vessel density parameter (all p > 0.05)

Discussion

The main finding of this study is that retrobulbar anesthesia did not induce any significant alteration in RPC plexus VD when assessed at postoperative week 1 and month 1. Moreover, no significant differences were observed between the retrobulbar and topical anesthesia groups at any time point. Furthermore, repeated-measures analysis revealed no significant group-by-time interaction, indicating that the longitudinal pattern of RPC VD change was similar in both anesthesia groups throughout the follow-up period. These results suggest that, with careful technique and ultrasound guidance, retrobulbar block does not induce measurable peripapillary microvascular compromise in uncomplicated cataract surgery.

Retrobulbar anesthesia is an effective regional technique, but it is associated with rare but potentially vision-threatening complications, including optic neuropathy [3, 4] Previous reports have attempted to explain optic neuropathy associated with retrobulbar injection using different methodologies. Ropo et al.⁸ demonstrated transient changes in visual evoked potentials (VEP) following retrobulbar injection and associated this with anesthesia-induced neurotoxicity. Lavinsky et al.¹³, on the other hand, evaluated VEP responses one month before and one month after cataract surgery and showed no significant difference between retrobulbar and peribulbar anesthesia groups. In addition to these electrophysiological studies evaluating optic nerve function, structural assessments were also needed. Kucuk et al.¹⁴ demonstrated that retrobulbar anesthesia did not cause significant changes and structural damage in the retinal nerve fiber layer (RNFL) after uncomplicated cataract surgery.

It has also been reported that vascular disruption may be a contributing factor to optic neuropathy after retrobulbar anesthesia. Coupland et al.⁵ demonstrated that regional orbital anesthesia resulted in a significant but partially reversible decrease in ocular blood flow indices. Todorich et al.⁶ demonstrated that retrobulbar block may be associated with transient intraoperative vascular stasis of the optic nerve and macula, possibly due to intraconal compartment syndrome, even in the absence of high intraocular pressure or hemorrhage. Huber et al.⁹ demonstrated, using colour Doppler imaging, that patients undergoing retrobulbar anesthesia experienced decreased velocities in the retrobulbar vessels immediately after anesthesia, but increased again after surgery. Given these results, objective in vivo microvascular assessments using OCTA will provide valuable information that was previously lacking.

Previous investigations of retrobulbar anesthesia have mainly evaluated optic nerve function using electrophysiological methods, structural changes using RNFL measurements, or ocular blood flow using Doppler-based techniques [5, 6, 8, 9, 13, 14] While these studies provided valuable information regarding the potential mechanisms of anesthesia-related optic nerve injury, they did not directly assess optic nerve head microvasculature. The present study extends the existing literature by providing an OCTA-based quantitative evaluation of RPC plexus VD following retrobulbar anesthesia and by comparing these findings with those obtained from a topical anesthesia control group.

Optical coherence tomography angiography provides important quantitative data on the VD of the RPC plexus, which plays a crucial role in supplying the RNFL [15] The VD of the RPC plexus is known to be susceptible to ischemic and glaucomatous optic neuropathies [16, 17] Akagi et al. [18] and Yarmohammadi et al. [19] demonstrated reductions in peripapillary VD in glaucomatous eyes compared to healthy controls. In contrast to these findings, no reduction in RPC plexus VD was detected after retrobulbar anesthesia in the present study. These findings indicate the absence of clinically significant microvascular damage.

The absence of significant intra-group changes from baseline to postoperative week 1 and month 1 in both anesthesia groups is also noteworthy. Phacoemulsification itself has been associated with transient changes in IOP and ocular perfusion dynamics, which could influence optic nerve head microcirculation [20, 21] Some studies have shown changes in RPC plexus VD after surgery, in association with intraoperative measurements such as CDE and IOP fluctuations [22] In addition, reports indicating an increase in RPC plexus VD after cataract surgery attribute this result to the preoperative measurements being underestimated, possibly due to the opacity of the optical media [23] To overcome this potential confounding issue, preoperative images with good signal strength and free from segmentation errors and artifacts were independently reviewed by two competent experts and included in the analysis. The results of the current study were consistent with those reports indicating stability of peripapillary perfusion after uncomplicated cataract extraction [24] Importantly, these studies were not focused on anesthesia type but on surgical technique and energy parameters. The lack of significant differences in surgical duration and CDE between groups further reduces the likelihood that surgical factors confounded the vascular outcomes.

Lidocaine is commonly used in retrobulbar anesthesia due to its rapid onset and favorable safety profile [2, 3] Epinephrine was added to prolong anesthetic duration and reduce systemic absorption by inducing local vasoconstriction [25] Retrobulbar anesthesia is thought to cause vasoconstriction, either mechanically or pharmacologically [26] Previous hemodynamic studies have suggested that the addition of epinephrine to local anesthetic solutions may enhance reductions in retrobulbar blood flow parameters [25] However, these effects are generally transient and may not necessarily result in detectable microvascular structural alterations. In the current study, no significant reduction in RPC VD was observed despite the use of epinephrine. The total dose was limited, and the injection was performed under ultrasound guidance following negative aspiration, avoiding intravascular administration. The lack of a significant decrease in RPC plexus VD suggests that the possible vasoconstrictive effect was minimal, transient, or did not exceed the threshold detectable by OCTA. Furthermore, it is possible that short-term perfusion changes were compensated for by autoregulatory mechanisms, maintaining stability in VD. The VD measurements obtained as a result of OCTA’s operating principle are actually an indirect indicator of perfusion. While it precisely detects structural microvascular changes, small changes in blood flow velocity may not be detected with current VD measurements.

The strengths of this study include its prospective design, strict exclusion criteria including confounding ocular comorbidities that could affect RPC plexus VD, analysis of OCTA scan signal strength index and segmentation assessments by two independent experts, ultrasound-guided retrobulbar anesthesia, and standardization of surgical parameters. Furthermore, comparison with results from a topical anesthesia control group allowed for the differentiation of the effects of anesthesia technique from the effects of surgery.

However, some limitations should be considered. While the sample size may have limited the ability to detect very subtle differences in VD, effect size estimates were uniformly small, all corresponding 95% CIs included zero, and no significant group-by-time interactions were detected, suggesting that any potential effect of retrobulbar anesthesia on RPC VD is likely to be small in magnitude. Systemic blood pressure and ocular perfusion pressure were not recorded at the time of OCTA acquisition. Although patients with systemic vascular diseases were excluded and the study groups were comparable in baseline characteristics, subtle interindividual variations in systemic hemodynamic status may have influenced OCTA-derived VD measurements. Therefore, the potential effect of systemic blood pressure changes between the preoperative and postoperative OCTA assessments cannot be completely excluded. Future studies incorporating simultaneous systemic blood pressure measurements and calculation of ocular perfusion pressure at each OCTA assessment may provide better control of this potential confounding factor. Another limitation is the absence of very early postoperative OCTA measurements. Although VD values remained stable at postoperative week 1 and month 1, transient microvascular or hemodynamic changes occurring within the first minutes, hours, or days after retrobulbar anesthesia may have been missed. Therefore, the present findings should be interpreted as evidence of the absence of persistent rather than immediate vascular effects. Future studies incorporating OCTA assessments immediately after retrobulbar injection and during the early postoperative period may provide additional insight into the acute microvascular response to retrobulbar anesthesia. Although several potential confounders were controlled through the study design, residual confounding cannot be completely excluded. Because both groups underwent the same phacoemulsification procedure under comparable surgical conditions, the influence of surgery-related factors was likely similar between groups. However, the independent contributions of cataract surgery and anesthesia technique cannot be completely disentangled within the present study design. In addition, results may differ in studies with different concentrations of anesthetic agents or in settings without imaging guidance.

Different methodological studies can make significant contributions to the literature on this subject. Studies including patients with glaucomatous or non-glaucomatous optic neuropathy can determine how the microvascular structure behaves under anesthesia-induced stress. The inclusion of additional structural and functional parameters such as RNFL thickness, ganglion cell complex analysis, and visual field may allow for the detection of subclinical structural or functional changes in the absence of detectable changes in RPC plexus VD. Comparative studies evaluating peribulbar or sub-Tenon’s anesthesia could additionally clarify whether different regional techniques exert distinct microvascular effects.

Although the present study yielded largely negative findings, it provides the first OCTA-based evaluation of RPC plexus microvasculature following retrobulbar anesthesia. Given the ongoing concerns regarding potential vascular mechanisms underlying retrobulbar anesthesia–associated optic nerve injury, these findings contribute objective in vivo evidence supporting the microvascular safety of this widely used anesthetic technique.

In conclusion, this OCTA-based study demonstrated that retrobulbar anesthesia was not associated with persistent changes in RPC plexus VD at postoperative week 1 or month 1 after phacoemulsification. No consistent trend toward lower VD was observed in the retrobulbar group compared with topical anesthesia, and the between-group differences were small and not clinically meaningful. These findings provide objective in vivo evidence regarding the microvascular effects of retrobulbar anesthesia and contribute to the limited literature on its potential impact on the optic nerve. Furthermore, they may help improve our understanding of the vascular mechanisms potentially involved in retrobulbar anesthesia–associated optic neuropathy.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contributions

ACY, HSS, OA and FMM contributed to the study design and literature review. Data were collected and the database was prepared by ACY and HSS. All authors contributed to the analysis of the data. ACY and HSS wrote the article. The article was supervised by OA and FMM.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Data availability

All clinical data of the study are located in a database in an Excel file. The data of the study can be obtained from the corresponding author upon request.

Declarations

Ethics approval and consent to participate

The study was approved by the University of Health Sciences Scientific Research Ethics Committee (approval no. 2025 − 578) on 23 December 2025. Patient recruitment commenced on 26 December 2025. The trial was retrospectively registered with the ISRCTN Registry (ISRCTN13084070). The full trial protocol is available at https://doi.org/10.1186/ISRCTN 13084070. All patients gave written informed consent for study participation following a detailed explanation of the study procedures.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.