Ophthalmic surgery is frequently performed in older adults who have coexisting cardiovascular, metabolic, and respiratory disorders. Contemporary cataract, glaucoma, and vitreoretinal procedures are increasingly undertaken using local or regional anaesthetic techniques because these approaches facilitate rapid recovery, preserve spontaneous ventilation, and reduce exposure to the physiological effects of general anaesthesia. Regional ophthalmic anaesthesia remains particularly useful when dense analgesia and ocular akinesia are required, especially for procedures in which eye movement can compromise surgical precision [6-10]. Common ophthalmic regional techniques include retrobulbar, peribulbar, and sub-Tenon blocks. Although these techniques are generally effective, conventional needle-based approaches depend largely on surface landmarks and tactile feedback. The orbit is a compact anatomical space containing the globe, optic nerve, extraocular muscles, vessels, and other vulnerable structures. Incorrect needle direction or unintended intraconal placement can therefore result in complications ranging from chemosis, ecchymosis, or subconjunctival haemorrhage to rare but serious events such as globe perforation, optic nerve injury, retrobulbar haemorrhage, local anaesthetic systemic toxicity, or brainstem anaesthesia [7,10-13]. Systematic reviews have shown that commonly used regional techniques provide satisfactory anaesthesia and akinesia, but no approach completely eliminates procedure-related risk [8,11,12]. Ultrasonography offers a logical method for improving anatomical orientation during ophthalmic regional anaesthesia. Real-time imaging can identify the globe, optic nerve, muscle cone, and abnormal ocular anatomy, while also allowing visualization of needle trajectory and the distribution of injected local anaesthetic [2-5]. Experimental and clinical work has demonstrated that ultrasound can show retro-orbital spread and that visible intraconal diffusion of local anaesthetic is strongly associated with successful akinesia [3,4]. More recent clinical studies have confirmed the feasibility of real-time ultrasound-guided retrobulbar or peribulbar blockade, with block characteristics and patient satisfaction comparable to conventional techniques [1,5]. Ultrasound also provides an opportunity to recognize anatomical variations or hazardous needle positions before injection, although operator skill, equipment suitability, and careful avoidance of excessive ocular pressure remain important [2,10,14]. Despite increasing interest, prospective clinical data describing routine ultrasound-guided ophthalmic regional anaesthesia across different elective eye procedures remain limited. Evidence from real-world practice is useful because effectiveness depends not only on sonographic needle visualization but also on onset time, quality of akinesia, analgesia, need for supplementation, surgical operating conditions, patient acceptance, and adverse events. The present study was therefore undertaken to evaluate the clinical effectiveness and complication profile of ultrasound-guided ophthalmic regional anaesthesia in adults undergoing elective eye surgery. The objectives were to determine primary block success, adequacy of sensory anaesthesia and ocular akinesia, requirement for supplementary anaesthesia or conversion to general anaesthesia, intraoperative pain, patient and surgeon satisfaction, and the frequency of block-related and perioperative complications.

Study design and setting This prospective observational study was conducted in the Department of Anaesthesiology at RVM Institute of Medical Sciences and Research Center, Laxmakkapally, Mulugu, Siddipet, Telangana, India, from September 2025 to May 2026. Adult patients scheduled for elective ophthalmic surgery in whom ultrasound-guided ophthalmic regional anaesthesia was planned were screened consecutively. Participants Patients aged 18 years or older with American Society of Anesthesiologists (ASA) physical status II or III who could cooperate with awake regional anaesthesia were eligible. Exclusion criteria included refusal, known hypersensitivity to the intended local anaesthetic, infection at the injection site, inability to cooperate, major orbital distortion precluding safe block performance, a contraindication to the planned regional technique, or incomplete perioperative observations. Eighty-four patients were assessed and 80 with complete evaluable data formed the final cohort. Sample size and sampling Sample size was estimated using n=Z²p(1-p)/d², assuming 95% confidence, 90% anticipated block success, and 7% absolute precision. The minimum was 71; allowing approximately 10% for incomplete observations, the target was rounded to 80 evaluable participants. Consecutive sampling was used throughout the study period. Ultrasound-guided block procedure Standard monitoring included non-invasive blood pressure, electrocardiography, and pulse oximetry, with intravenous access secured before the block. With the patient supine and the eye in neutral gaze, ultrasound scanning was performed over the closed eyelid using minimal probe pressure. The globe, optic nerve, extraocular muscles, and intended orbital compartment were identified. Under aseptic precautions, the block needle was advanced under ultrasound visualization toward the planned target while avoiding the globe and visible vulnerable structures. After negative aspiration, local anaesthetic was injected incrementally while orbital spread was observed. Local anaesthetic selection and concentration followed institutional protocol and procedural requirements. The sonographic principles were consistent with previously described ophthalmic ultrasound-guided techniques [2-5]. Outcome assessment The primary outcome was block success, defined as surgery completed without additional regional local anaesthetic or conversion to general anaesthesia. Secondary outcomes included local anaesthetic volume, block performance time, sensory onset, adequate ocular akinesia within 10 minutes, complete sensory anaesthesia, supplementation, conversion to general anaesthesia, duration of surgery, and intraoperative pain measured on an 11-point numerical rating scale (NRS; 0=no pain and 10=worst imaginable pain). Patient and surgeon satisfaction were recorded after surgery; satisfied and very satisfied responses were combined. Prespecified complications included subconjunctival haemorrhage, periorbital ecchymosis, chemosis, injection-site discomfort, oculocardiac bradycardia, nausea or vomiting, retrobulbar haemorrhage, globe perforation, optic nerve injury, local anaesthetic systemic toxicity, and respiratory compromise [7,10-14]. Statistical analysis and ethics Continuous variables were summarized as mean ± standard deviation when approximately normally distributed and as median with interquartile range for skewed or ordinal data. Categorical variables were expressed as frequencies and percentages. As the study was descriptive and had no comparison group, inferential between-group testing was not planned. Necessary Permissions were obtained before starting the study, and written informed consent was obtained from all participants.

A total of 84 patients scheduled for elective ophthalmic surgery under ultrasound-guided regional anaesthesia were assessed for eligibility. Four patients were excluded because of incomplete perioperative observations or failure to satisfy the predefined eligibility criteria. Consequently, 80 patients were included in the final analysis. The mean age of the study population was 64.8 ± 9.7 years, and 44 (55.0%) participants were male. The mean body mass index was 24.9 ± 3.4 kg/m². Forty-nine patients (61.3%) were classified as ASA physical status II and 31 (38.8%) as ASA physical status III. Hypertension was the most frequent comorbidity, affecting 39 (48.8%) patients, followed by diabetes mellitus in 27 (33.8%) and ischaemic heart disease in 8 (10.0%). Cataract surgery was the most common procedure, accounting for 58 (72.5%) cases; the remaining operations included vitreoretinal, glaucoma, and other elective ophthalmic procedures (Table 1). Table 1. Baseline clinical and surgical characteristics of the study participants (n = 80) Characteristic n (%) / Mean ± SD Age, years 64.8 ± 9.7 Male 44 (55.0) Female 36 (45.0) BMI, kg/m² 24.9 ± 3.4 ASA physical status II 49 (61.3) ASA physical status III 31 (38.8) Hypertension 39 (48.8) Diabetes mellitus 27 (33.8) Ischaemic heart disease 8 (10.0) Cataract surgery 58 (72.5) Vitreoretinal surgery 13 (16.3) Glaucoma surgery 6 (7.5) Other ophthalmic procedures 3 (3.8) The mean volume of local anaesthetic administered was 5.6 ± 1.1 mL. Mean block performance time was 4.8 ± 1.6 minutes, and satisfactory sensory anaesthesia developed after a mean of 4.3 ± 1.5 minutes. Adequate ocular akinesia within 10 minutes was achieved in 74 (92.5%) patients, while complete sensory anaesthesia was documented in 76 (95.0%). The mean surgical duration was 54.6 ± 21.8 minutes (Table 2). Table 2. Procedural and block characteristics (n = 80) Parameter n (%) / Mean ± SD Local anaesthetic volume, mL 5.6 ± 1.1 Block performance time, min 4.8 ± 1.6 Sensory block onset, min 4.3 ± 1.5 Adequate akinesia within 10 min 74 (92.5) Complete sensory anaesthesia 76 (95.0) Successful block without supplementation 73 (91.3) Additional local anaesthetic required 7 (8.8) Conversion to general anaesthesia 1 (1.3) Duration of surgery, min 54.6 ± 21.8 Primary block success, defined as completion of surgery without additional regional anaesthetic supplementation or conversion to general anaesthesia, was achieved in 73 (91.3%) patients. Seven patients (8.8%) required supplementary local anaesthetic because of incomplete akinesia or intraoperative discomfort. Six of these subsequently completed surgery satisfactorily under regional anaesthesia, whereas one patient (1.3%) required conversion to general anaesthesia. Thus, 79 (98.8%) of the 80 procedures were completed under regional anaesthesia. Intraoperative pain was generally low. The median NRS pain score was 1 (IQR 0–2). Sixty-nine patients (86.3%) reported no pain or minimal pain (NRS 0–2), 9 (11.3%) experienced mild-to-moderate discomfort, and 2 (2.5%) required intravenous rescue analgesia. Seventy-five patients (93.8%) were satisfied or very satisfied with the anaesthetic technique, while surgeons rated operating conditions as satisfied or very satisfied in 74 (92.5%) procedures (Table 3). Table 3. Clinical effectiveness and patient comfort (n = 80) Outcome n (%) / Value Primary block success 73 (91.3) Surgery completed under regional anaesthesia 79 (98.8) Intraoperative NRS pain score, median (IQR) 1 (0–2) No/minimal pain (NRS 0–2) 69 (86.3) Mild-to-moderate pain (NRS 3–4) 9 (11.3) Rescue intravenous analgesia required 2 (2.5) Patient satisfied/very satisfied 75 (93.8) Surgeon satisfied/very satisfied 74 (92.5) Block-related and perioperative complications were infrequent and predominantly minor. Subconjunctival haemorrhage occurred in 5 (6.3%) patients, injection-site discomfort in 4 (5.0%), periorbital ecchymosis in 3 (3.8%), and transient chemosis in 3 (3.8%). One patient (1.3%) developed transient bradycardia consistent with an oculocardiac response, and 2 (2.5%) experienced nausea or vomiting. No retrobulbar haemorrhage, globe perforation, optic nerve injury, local anaesthetic systemic toxicity, or respiratory compromise was observed (Table 4). Table 4. Block-related and perioperative complications (n = 80) Complication n (%) Subconjunctival haemorrhage 5 (6.3) Periorbital ecchymosis 3 (3.8) Chemosis 3 (3.8) Injection-site discomfort 4 (5.0) Transient bradycardia/oculocardiac response 1 (1.3) Nausea/vomiting 2 (2.5) Retrobulbar haemorrhage 0 Globe perforation 0 Optic nerve injury 0 Local anaesthetic systemic toxicity 0 Respiratory compromise 0 Haemodynamic parameters remained clinically stable throughout the perioperative period. Minor transient changes in heart rate or blood pressure did not require termination of surgery. There were no unplanned intensive care admissions or serious anaesthesia-related adverse events. Overall, ultrasound-guided ophthalmic regional anaesthesia was associated with a primary block success rate of 91.3%, completion of surgery under regional anaesthesia in 98.8%, low intraoperative pain, high patient and surgeon satisfaction, and a low frequency of predominantly minor complications.

In this prospective observational cohort, ultrasound-guided ophthalmic regional anaesthesia provided effective operating conditions for most elective eye procedures. Primary block success without supplementation was 91.3%, complete sensory anaesthesia was achieved in 95.0%, and adequate akinesia within 10 minutes occurred in 92.5%. Importantly, 79 of 80 patients completed surgery under regional anaesthesia, with only one conversion to general anaesthesia. Intraoperative pain remained low, and both patient and surgeon satisfaction exceeded 92%. These findings support the practical effectiveness of ultrasound-guided orbital blockade in a clinically heterogeneous elective ophthalmic population. The observed performance is consistent with the concept that sonography can improve understanding of needle position and injectate distribution. Gayer and Palte emphasized that conventional ophthalmic blocks cannot reliably predict final needle-tip location and that visualization of local anaesthetic spread is a central advantage of ultrasound guidance [2]. Luyet et al. demonstrated real-time retrobulbar needle visualization in an imaging study and later showed that sonographically evident intraconal spread during peribulbar injection strongly predicted successful akinesia [3,4]. In their prospective study, clear intraconal spread had a positive predictive value of 98% for successful block, although rescue block requirements were higher than in the present cohort [4]. Differences in patient selection, procedure type, block technique, operator experience, and outcome definitions can account for this variation. Clinical comparative studies have also shown that ultrasound-guided techniques are feasible without compromising block quality. Foad et al. found similar onset, pain scores, supplementation, and satisfaction between real-time ultrasound-guided and conventional retrobulbar blocks [5]. More recently, Naguib et al. reported comparable onset and block quality with ultrasound-guided and conventional peribulbar anaesthesia, with direct visualization offering a potential advantage in identifying vulnerable anatomy [1]. The present findings extend these observations to a broader group of elective ophthalmic operations rather than cataract surgery alone. The complication pattern was predominantly minor. Subconjunctival haemorrhage, injection-site discomfort, periorbital ecchymosis, and chemosis occurred at low frequencies, while no retrobulbar haemorrhage, globe perforation, optic nerve injury, local anaesthetic systemic toxicity, or respiratory compromise was recorded. Minor local events are recognized across ophthalmic regional techniques, whereas severe complications are uncommon but clinically important [7,10-13]. Schrader et al. described substantial visual morbidity following inadvertent globe perforation with needle-based blocks [13], and Sadler et al. demonstrated that ultrasound can depict patterns of unintended orbital injection in a cadaveric model [14]. The absence of serious complications in 80 patients should therefore be interpreted as reassuring clinical experience rather than proof that ultrasound eliminates rare adverse events. Overall, the combination of high block success, low pain scores, limited supplementation, favourable satisfaction, and few minor complications suggests that ultrasound-guided ophthalmic regional anaesthesia can be integrated effectively into elective eye surgery when performed by clinicians familiar with orbital anatomy and ultrasound technique. LIMITATIONS This study has several limitations. It was conducted at a single centre with a modest sample size and lacked a conventional landmark-guided comparison group. The cohort included different ophthalmic procedures, introducing procedural heterogeneity. Rare sight-threatening or life-threatening complications cannot be reliably estimated from 80 participants. Operator experience was not analysed separately, and longer-term postoperative outcomes beyond the immediate perioperative period were not evaluated.

Ultrasound-guided ophthalmic regional anaesthesia demonstrated a high level of clinical effectiveness in adults undergoing elective eye surgery. Most patients achieved timely ocular akinesia and complete sensory anaesthesia, while more than nine in ten blocks were successful without additional regional supplementation. Nearly all procedures were completed under regional anaesthesia, with low intraoperative pain and high patient and surgeon satisfaction. Adverse events were uncommon and predominantly minor, and no major ocular, neurological, systemic local-anaesthetic, or respiratory complication was observed. These findings support ultrasound guidance as a practical approach for ophthalmic regional anaesthesia when appropriate equipment and operator expertise are available. Larger comparative multicentre studies are required to define its incremental safety advantage over conventional techniques.

1. Naguib NN, Mohasseb TM, Ezzat AM, Hussien GZ, Khattab RS, Aboul Fetouh ES, et al. Ultrasound-guided versus conventional peribulbar anaesthesia in cataract surgery: A randomised controlled study. J Perioper Pract. 2023;33(10):302-307. doi:10.1177/17504589221117670. 2. Gayer S, Palte HD. Ultrasound-guided ophthalmic regional anesthesia. Curr Opin Anaesthesiol. 2016;29(6):655-661. doi:10.1097/ACO.0000000000000393. 3. Luyet C, Eichenberger U, Moriggl B, Remonda L, Greif R. Real-time visualization of ultrasound-guided retrobulbar blockade: an imaging study. Br J Anaesth. 2008;101(6):855-859. doi:10.1093/bja/aen293. 4. Luyet C, Eng KT, Kertes PJ, Avila A, Muni RH, McHardy P. Real-time evaluation of diffusion of the local anesthetic solution during peribulbar block using ultrasound imaging and clinical correlates of diffusion. Reg Anesth Pain Med. 2012;37(4):455-459. doi:10.1097/AAP.0b013e31825541e8. 5. Foad AZ, Mansour MA, Ahmed MB, Elgamal HR, Ibrahim HEE, Elawamy A. Real-time ultrasound-guided retrobulbar block vs blind technique for cataract surgery (pilot study). Local Reg Anesth. 2018;11:123-128. doi:10.2147/LRA.S178771. 6. Jaichandran VV. Ophthalmic regional anaesthesia: A review and update. Indian J Anaesth. 2013;57(1):7-13. doi:10.4103/0019-5049.108552. 7. Kumar C, Dowd T. Ophthalmic regional anaesthesia. Curr Opin Anaesthesiol. 2008;21(5):632-637. doi:10.1097/ACO.0b013e32830abc09. 8. Chua MJ, Lersch F, Chua AWY, Kumar CM, Eke T. Sub-Tenon's anaesthesia for modern eye surgery-clinicians' perspective, 30 years after re-introduction. Eye (Lond). 2021;35(5):1295-1304. doi:10.1038/s41433-021-01412-5. 9. McRae L, Presland A. A review of current ophthalmic anaesthetic practice. Br Med Bull. 2020;135(1):62-72. doi:10.1093/bmb/ldaa022. 10. Palte HD. Ophthalmic regional blocks: management, challenges, and solutions. Local Reg Anesth. 2015;8:57-70. doi:10.2147/LRA.S64806. 11. Alhassan MB, Kyari F, Ejere HOD. Peribulbar versus retrobulbar anaesthesia for cataract surgery. Cochrane Database Syst Rev. 2015;2015(7):CD004083. doi:10.1002/14651858.CD004083.pub3. 12. Wang BZ, Casson R. Systematic review of peribulbar anesthesia versus sub-Tenon anesthesia for cataract surgery. Asia Pac J Ophthalmol (Phila). 2012;1(3):170-174. doi:10.1097/APO.0b013e31825215e2. 13. Schrader WF, Schargus M, Schneider E, Josifova T. Risks and sequelae of scleral perforation during peribulbar or retrobulbar anesthesia. J Cataract Refract Surg. 2010;36(6):885-889. doi:10.1016/j.jcrs.2009.12.029. 14. Sadler A, McLeod G, McHardy PG, Wilkinson T. Ultrasound detection of iatrogenic injury during peribulbar eye block: a cadaveric study. Reg Anesth Pain Med. 2020;45(9):740-743. doi:10.1136/rapm-2020-101433.