1.1 The Laparoscopic Revolution and Its Ocular Consequences Laparoscopic surgery has transformed the management of common abdominal conditions over the past four decades. Three of the most frequently performed laparoscopic procedures in any general surgical unit are laparoscopic cholecystectomy (LC) for symptomatic cholelithiasis, laparoscopic appendectomy (LA) for acute appendicitis, and laparoscopic inguinal hernia repair (TAPP — Transabdominal Preperitoneal; TEP — Totally Extraperitoneal) for inguinal hernia. Together, these three procedures account for the vast majority of elective and semi-emergency laparoscopic workload in Indian medical colleges. While their advantages over open surgery are well established — reduced postoperative pain, shorter hospitalization, faster recovery — their systemic physiological consequences are increasingly recognized as clinically important, particularly with respect to intraocular pressure (IOP) and intracranial pressure (ICP) 1.2 Physiology of IOP and ICP Elevation During Laparoscopy All laparoscopic procedures require CO₂ pneumoperitoneum, typically at 12–15 mmHg. The creation of a pneumoperitoneum raises intra-abdominal pressure (IAP), which elevates intrathoracic pressure, which in turn increases central venous pressure (CVP). This rise in CVP impedes venous drainage from the episcleral veins via the superior ophthalmic vein, resulting in raised episcleral venous pressure and consequently elevated IOP. Simultaneously, CO₂ absorption across the peritoneal surface produces systemic hypercapnia (raised PaCO₂), causing cerebral vasodilation, raised cerebral blood flow, and ultimately raised ICP. Raised ICP is transmitted to the perioptic subarachnoid space — which communicates freely with the intracranial subarachnoid space through the optic nerve sheath — producing measurable optic nerve sheath diameter (ONSD) expansion detectable non-invasively on B-mode ultrasonography. Critically, the patient positioning adopted for each laparoscopic procedure profoundly modifies the magnitude of these effects. Laparoscopic cholecystectomy uses reverse Trendelenburg (head-up) positioning, which partially counteracts venous congestion by promoting cephalic venous drainage. In contrast, laparoscopic appendectomy and TAPP/TEP hernia repair utilize Trendelenburg (head-down) positioning, which compounds the effect of pneumoperitoneum by adding gravitational venous pooling toward the head, resulting in greater IOP and ICP elevation. This positional dichotomy creates a natural comparative framework for this study. 1.3 Evidence from Existing Literature Existing evidence reveals a striking gradient of IOP effects across these procedures. A prospective study from Zagazig University reported that IOP rose from a baseline of 15.21 ± 1.61 mmHg to 24.55 ± 6.28 mmHg during LC (p < 0.001), attributable primarily to pneumoperitoneum in reverse Trendelenburg. At the other extreme, studies of steep Trendelenburg procedures (robotic prostatectomy, 45° tilt) reported IOP values rising from 19.9 mmHg at baseline to 33.9 mmHg at maximum surgical dissection, with ONSD remaining permanently above 6.0 mm throughout surgery — a threshold indicative of raised ICP. In laparoscopic pelvic surgery, Trendelenburg positioning combined with pneumoperitoneum raised IOP above the normal limit of 22 mmHg even with propofol anaesthesia, and higher still with desflurane. The data for TAPP/TEP hernia repair is particularly interesting: a 50-patient prospective study comparing TAPP (n=25) and TEP (n=25) found no statistically significant intraoperative IOP change in either group (p = 0.357), despite the use of Trendelenburg positioning and pneumoperitoneum. This contrasts sharply with appendectomy data and raises the important question of whether the degree and duration of head-down tilt rather than pneumoperitoneum alone is the dominant determinant of IOP elevation — a question that this multi-procedure comparative study is uniquely positioned to answer. For ONSD, a Korean study on steep Trendelenburg patients demonstrated that ONSD increased significantly to 5.1 ± 0.3 mm within just 3 minutes of head-down positioning alone (before pneumoperitoneum), confirming that position is an independent contributor to raised ICP. A Turkish study further showed that ONSD values increased in direct proportion to intra-abdominal pressure at 10, 12, and 14 mmHg during LC. Importantly, a Japanese obesity study found that in obese patients, raised ONSD did not return to baseline even 24 hours after desufflation, raising serious concerns about recovery in high-risk populations. 1.4 The Glaucoma Suspect: A Vulnerable Subgroup In healthy eyes with normal optic nerve architecture, transient intraoperative IOP surges are generally tolerated without lasting structural damage. The situation is fundamentally different in glaucoma suspects — patients with IOP > 21 mmHg (ocular hypertension), suspicious cup-to-disc ratio (CDR ≥ 0.6), narrow anterior chamber angles (Van Herick Grade 1–2), or suspicious visual fields. The AAO Preferred Practice Pattern defines a glaucoma suspect as any patient with one or more of: consistently elevated IOP, suspicious optic nerve or RNFL, or abnormal visual fields. In these patients, an acute intraoperative IOP surge — particularly when sustained for the duration of a laparoscopic procedure — may critically reduce optic nerve perfusion pressure (defined as mean arterial pressure minus IOP), risking ischemic optic neuropathy or perioperative visual loss (POVL). POVL is rare but catastrophic, and no Indian multi-centre study has addressed its perioperative laparoscopic risk stratification. 1.5 Research Gap and Justification To date, no published Indian study has: (a) simultaneously compared IOP and ONSD changes across three different laparoscopic abdominal procedures in a single prospective cohort; (b) prospectively identified and separately analysed a glaucoma suspect subgroup across all three procedure types; or (c) evaluated the recovery kinetics of IOP and ONSD into the postoperative period across these procedures. This study directly fills these three gaps, with output that can generate the first Indian evidence-based recommendation for mandatory pre-operative ophthalmic screening before laparoscopic abdominal surgery. 2. AIMS AND OBJECTIVES 2.1 Primary Aim To prospectively compare intraoperative IOP and ONSD changes across three laparoscopic abdominal procedures — laparoscopic cholecystectomy, laparoscopic appendectomy, and TAPP/TEP hernia repair — and to characterize the recovery of these parameters in the postoperative period. 2.2 Secondary Aims • To compare IOP and ONSD changes between normal ophthalmic patients and pre-operatively identified glaucoma suspects within each procedure group. • To determine which laparoscopic procedure poses the greatest risk of IOP elevation and ICP transmission to the optic nerve sheath. • To correlate IOP and ONSD changes with intra-abdominal pressure, patient positioning angle, end-tidal CO₂ (EtCO₂), mean arterial pressure (MAP), operative duration, and BMI. • To establish the rate of previously undiagnosed glaucoma suspects in patients presenting for elective laparoscopic abdominal surgery at a tertiary care medical college. • To assess the feasibility and clinical utility of a structured pre-operative ophthalmic screening protocol for all laparoscopic surgical candidates. 2.3 Hypotheses Null Hypothesis (H₀): There is no significant difference in IOP or ONSD changes across laparoscopic cholecystectomy, appendectomy, and TAPP/TEP hernia repair. Alternate Hypothesis (H₁): Laparoscopic procedures using Trendelenburg (head-down) positioning — appendectomy and TAPP/TEP — produce significantly greater IOP and ONSD elevation compared to reverse Trendelenburg procedures (LC), with disproportionately greater and more prolonged elevation in glaucoma suspects. 3. STUDY DESIGN AND SETTING Parameter Details Study Design Prospective comparative observational study with concurrent subgroup analysis Study Setting Departments of General Surgery, Ophthalmology, and Anaesthesiology — [Institution Name] Study Population Adult patients undergoing elective/semi-elective laparoscopic abdominal surgery Duration 12 months: Month 1–2 (ethics/preparation), Month 3–11 (data collection), Month 12 (analysis/writing) Ethics IEC approval mandatory before first enrolment; CTRI registration required Blinding Ophthalmologist measuring IOP and ONSD will be blinded to surgical findings and IAP readings; data entry personnel blinded to group assignment during analysis Consent Written informed consent in English, Hindi, and regional language; 24-hour reflection period 4.2 Inclusion Criteria (All Groups) • Age 18–70 years • Confirmed diagnosis requiring elective or semi-elective laparoscopic abdominal surgery (cholelithiasis confirmed by USG for Group A; clinical/imaging diagnosis of acute uncomplicated appendicitis for Group B; inguinal hernia clinically confirmed ± USG for Group C) • ASA Physical Status Class I or II • Written informed consent obtained No previous intraocular surgery or known end-stage structural ocular disease 4. STUDY GROUPS AND ELIGIBILITY CRITERIA 4.1 Study Groups Group Procedure Operative Position Expected IOP Effect n (Total) n (Suspects) Group A Laparoscopic Cholecystectomy (LC) Reverse Trendelenburg 15–20° (head UP) Moderate elevation — pneumoperitoneum partially offset by head-up 50 10 Group B Laparoscopic Appendectomy (LA) Trendelenburg 15–20° (head DOWN) Higher elevation — pneumoperitoneum + head-down additive 50 10 Group C TAPP / TEP Hernia Repair Modified Trendelenburg 10–15° Variable — prior study showed no significant change; to be confirmed 50 10 TOTAL All three procedures — — 150 30 4.3 Exclusion Criteria • Emergency laparotomy/conversion to open surgery intraoperatively (excluded from final analysis) • Pre-existing severe/end-stage glaucoma with documented structural damage and field loss • Known raised ICP (hydrocephalus, intracranial neoplasm, idiopathic intracranial hypertension) • Use of systemic or topical medications significantly affecting IOP (systemic corticosteroids, anti-glaucoma eye drops) • Severe periorbital/conjunctival pathology precluding IOP measurement • Pregnancy or suspected pregnancy • Prior laparoscopic surgery within 6 months (to exclude adhesion-related IAP alterations) • Withdrawal of consent at any point 4.4 Glaucoma Suspect Subgroup Definition (AAO Preferred Practice Pattern) Within each procedure group, 10 patients will be prospectively identified as Glaucoma Suspects if they satisfy one or more of: • IOP > 21 mmHg on two separate measurements (Tono-Pen applanation tonometry) — Ocular Hypertension • Cup-to-disc ratio (CDR) ≥ 0.6 in either eye, or asymmetry ≥ 0.2 between eyes on dilated fundoscopy • Van Herick Grade 1 or 2 on slit-lamp anterior chamber angle assessment (narrow/occludable angle) • Suspicious visual field defect on confrontation perimetry or reported history of visual disturbance 5. SAMPLE SIZE CALCULATION 5.1 Basis for Calculation Sample size is based on the primary outcome of IOP change from baseline to peak intraoperative measurement. Published data provide the following reference values for a two-group comparison (LC reverse Trendelenburg vs. Trendelenburg procedures): Parameter Value / Source Baseline mean IOP (pre-operative) ~15 mmHg (across published studies) Expected mean IOP at peak (reverse Trendelenburg — LC) ~22–25 mmHg (Zagazig study, 2016) Expected mean IOP at peak (Trendelenburg — LA/TAPP) ~25–30 mmHg (extrapolated from colorectal + pelvic lap data) Expected difference between groups ~6–8 mmHg Pooled standard deviation (from published LC/laparoscopy studies) ~6.3 mmHg Alpha (α) — Type I error (two-tailed) 0.05 Power (1−β) 80% Calculated n per group (one-way ANOVA, 3 groups) ~39 patients per group Rounded up (to allow for 20% dropout/conversion) 50 per group Glaucoma suspect subgroup (10 per group x 3 groups) 30 total (already included within 150) TOTAL SAMPLE SIZE 150 patients Sample size calculated using one-way ANOVA formula for three independent groups. The 150-patient total is achievable within 9 months at a medical college performing ≥20 laparoscopic procedures per month across all three categories combined. 6. DETAILED METHODOLOGY 6.1 Pre-Operative Assessment (All Patients) Within 48 hours before surgery, every enrolled patient will undergo a structured pre-operative ophthalmic evaluation performed by a trained ophthalmologist (or supervised postgraduate resident under direct supervision). This evaluation will constitute the T0 (baseline) measurement for all parameters and will serve simultaneously as the glaucoma suspect screening protocol. Components include: • Best-corrected visual acuity (BCVA) — Snellen chart, 6-metre distance • Slit-lamp anterior segment examination including Van Herick peripheral anterior chamber depth grading (Grade 0–4) • Intraocular pressure — Non-contact tonometer (NCT/air-puff), three readings averaged, both eyes — used pre-operatively and post-operatively after full recovery from anaesthesia • Posterior segment examination — dilated fundoscopy with 90D/78D lens; optic disc CDR documented for both eyes • Baseline ONSD measurement — B-mode ultrasonography (7.5–10 MHz linear probe), both eyes, three readings averaged, measurement taken 3 mm posterior to posterior globe wall • Brief confrontation perimetry to screen for visual field defects Patients meeting glaucoma suspect criteria are allocated to the suspect subgroup (n=10 per procedure group), counselled appropriately, and referred for formal ophthalmology clinic follow-up post-discharge regardless of study outcome. 6.2 Anaesthetic Protocol — Standardized Across All Groups All patients in all three groups will receive standard general anaesthesia (GA) administered by the Department of Anaesthesiology per institutional protocol. The anaesthetic agent (inhalational or intravenous) will be recorded but not mandated — reflecting real-world practice and ensuring broad generalizability of findings. It is acknowledged that published evidence shows propofol attenuates IOP elevation compared to volatile agents; therefore, the anaesthetic agent used will be recorded and included as a covariate in the statistical analysis to control for its effect. Neuromuscular blockade with vecuronium (0.1 mg/kg) and reversal with neostigmine + glycopyrrolate will be standard. Ventilation will be volume-controlled; end-tidal CO₂ (EtCO₂) will be maintained at 35–40 mmHg in all cases. Pneumoperitoneum will be established at 12 mmHg IAP for Groups A and B, and 10–12 mmHg for Group C (TEP/TAPP standard practice). Actual IAP, tilt angle, EtCO₂, MAP, SpO₂, peak inspiratory pressure (PIP), heart rate, and anaesthetic agent used will be recorded at each IOP/ONSD measurement time point. 6.3 Intraoperative Measurement Protocol — Six Standardized Time Points IOP and ONSD measurements will be performed at identical time points across all three groups by a single trained ophthalmology team member (to ensure intra-observer consistency). Measurements are taken at the patient's head, outside the sterile surgical field, using sterile probe covers and standard aseptic technique: Time Point Label Clinical Moment Remarks T0 Pre-operative Baseline Awake patient in ophthalmology clinic 24–48h before surgery NCT (non-contact tonometer); B-mode USG for ONSD T1 Post-induction After GA induction; before CO₂ insufflation; supine position Captures GA effect on IOP independent of pneumoperitoneum; anaesthetic agent recorded T2 Pneumoperitoneum + Position 15 min 15 min after pneumoperitoneum established at target IAP, in operative position Peak early phase — captures combined pneumoperitoneum + position effect T3 Pneumoperitoneum + Position 30 min 30 min after pneumoperitoneum in operative position Sustained phase — most clinically relevant T4 Post-desufflation 10 min 10 min after complete CO₂ desufflation; patient supine; still intubated Captures immediate recovery T5 Post-operative 8 hours 8 hours after surgery; patient awake in ward Captures full recovery or persistent elevation T6 Post-operative 24 hours 24 hours post-surgery (added for obese subgroup and suspects) Recovery in high-risk patients — evidence shows delayed recovery in obese 6.3.1 IOP Measurement Technique A two-instrument standardized protocol will be used for IOP measurement, with each instrument allocated to specific time points based on patient cooperation and clinical feasibility: Pre-operative and post-anaesthesia recovery (T0, T5, T6 — Awake Patient): Non-contact tonometer (NCT / air-puff tonometer) — The patient is awake, cooperative, and seated or lying still. NCT requires no topical anaesthesia, eliminates infection risk, avoids corneal contact, and is the most reproducible method in conscious patients. Three readings per eye are taken and averaged. Intraoperative under general anaesthesia (T1, T2, T3, T4 — Anaesthetized Patient): Tono-Pen AVIA applanation tonometer — The patient is intubated and anaesthetized; NCT is not feasible as it requires patient fixation and cooperation. The Tono-Pen is applied directly to the conjunctival surface through the lightly retracted eyelid under sterile conditions. No topical anaesthesia is required as the patient is under GA. Three readings per eye per time point are averaged. The use of two instruments is a deliberate methodological choice aligned with clinical practicality. Inter-device variability is controlled by: (a) using each instrument exclusively and consistently within its designated patient state (awake vs. anaesthetized); (b) recording both the pre-induction NCT value (T0) and the post-induction Tono-Pen value (T1, before pneumoperitoneum) — the T1 vs. T0 difference thus also quantifies the GA-induced IOP drop and serves as an internal calibration reference; and (c) NCT and Tono-Pen measurements will be taken simultaneously on a subset of 20 awake patients pre-operatively to establish a device correlation coefficient for this study population, enabling appropriate statistical adjustment if needed. IOP > 21 mmHg is flagged as elevated; IOP ≥ 25 mmHg is a critical value requiring post-operative ophthalmology documentation. 6.3.2 ONSD Measurement Technique A 7.5–10 MHz linear ultrasound probe is applied to the closed eyelid with generous aqueous coupling gel and a sterile probe cover. The globe is imaged in B-mode in transverse orientation. The posterior wall of the globe is identified as a hyperechoic line. The measurement cursor is placed exactly 3 mm posterior to the posterior globe wall and the width of the hypoechoic optic nerve sheath (internal sheath-to-sheath measurement) is recorded. Three measurements per eye per time point are taken and averaged; the mean of both eyes constitutes the study value. ONSD ≥ 5.5 mm is used as the threshold for raised ICP (sensitivity 100%, specificity 75% for ICP > 20 mmHg in published validation studies). All intraoperative USG measurements are performed in under 90 seconds to avoid disturbing surgical workflow. 6.4 Procedure-Specific Notes Group Specific Considerations Group A — LC Reverse Trendelenburg 15–20°; pneumoperitoneum 12 mmHg; 4-port standard technique; expected operative time 45–75 min Group B — LA Trendelenburg 15–20°; pneumoperitoneum 12 mmHg; 3-port technique; expected operative time 30–60 min; note: appendicitis patients may have mild pre-existing physiological stress — baseline MAP and EtCO₂ will be carefully co-varied Group C — TAPP/TEP Modified Trendelenburg 10–15°; TAPP at 12 mmHg; TEP at 10–12 mmHg; record which technique used; expected operative time 45–90 min; note prior study found no significant IOP change — confirm/refute with ONSD data 6.5 Case Record Form (CRF) A structured CRF will capture: Demographics (age, sex, BMI, comorbidities — DM, HTN, dyslipidaemia); Surgical details (procedure type, technique, IAP, Trendelenburg angle, operative duration, conversions, complications); Anaesthetic parameters (agent used — inhalational/IV, EtCO₂, MAP, PIP, SpO₂ at each time point); Ophthalmic measurements (Tono-Pen IOP and ONSD at T0–T6 for both eyes); Glaucoma suspect classification (yes/no, criteria met); Post-operative outcomes (any visual complaints, headache, PONV within 24h). 7. STATISTICAL ANALYSIS PLAN 7.1 Descriptive Statistics Continuous variables will be presented as mean ± SD (if normally distributed — assessed by Shapiro-Wilk test) or median (IQR) (if non-normal). Categorical variables as frequencies and percentages. Baseline characteristics will be compared across three groups using one-way ANOVA (continuous) or chi-square test (categorical) to confirm group comparability. 7.2 Primary Analysis • Within each group: Repeated measures ANOVA (or Friedman test if non-normal) to assess IOP and ONSD changes across T0–T6. Post-hoc pairwise comparisons using Bonferroni correction. • Across groups: One-way ANOVA (or Kruskal-Wallis) comparing the magnitude of IOP change (T3 minus T0) and ONSD change (T3 minus T0) between Groups A, B, and C. Post-hoc Tukey HSD for pairwise inter-group comparisons. • Primary endpoint: Delta-IOP (T3−T0) and Delta-ONSD (T3−T0) compared across three procedure groups. 7.3 Secondary Analysis • Independent t-test (or Mann-Whitney U) within each group: Glaucoma suspects vs. non-suspects for IOP and ONSD changes at each time point. • Recovery analysis: Time-to-return-to-baseline IOP and ONSD modelled using mixed-effects longitudinal analysis. • Correlation analysis: Pearson/Spearman correlation of Delta-IOP and Delta-ONSD with IAP, EtCO₂, MAP, PIP, operative duration, Trendelenburg angle, and BMI. • Logistic regression: Independent predictors of clinically significant IOP elevation (≥25 mmHg) and ONSD elevation (≥5.5 mm) — procedure type, position, IAP, BMI, glaucoma suspect status. • Subgroup analysis in glaucoma suspects (n=30): Three-group comparison of IOP and ONSD using same framework as primary analysis. 7.4 Software and Significance Threshold SPSS v26.0 (IBM) or GraphPad Prism v9. All tests two-tailed; p < 0.05 considered statistically significant. Bonferroni correction applied for multiple comparisons. 9. ETHICAL CONSIDERATIONS 9.1 Nature of Study and Risk Assessment This is a non-interventional, observational study. No modification to standard surgical technique, anaesthetic protocol, or postoperative care will be made. General anaesthesia will be administered per the standard institutional protocol. IOP measurement by Tono-Pen applanation tonometry and ONSD by ultrasonography are established safe, non-invasive procedures. The only addition to standard care is the addition of a pre-operative ophthalmic examination, which carries no risk and yields direct clinical benefit for any newly identified glaucoma suspect. 9.2 Benefit to Participants Every participant receives a comprehensive pre-operative ophthalmic evaluation at no cost — including IOP measurement, disc assessment, and anterior chamber angle grading — which they may not otherwise receive. Newly identified glaucoma suspects receive formal ophthalmology referral. This constitutes a direct, tangible clinical benefit beyond the research objectives. 9.3 Regulatory and Ethical Framework • Declaration of Helsinki (World Medical Association, revised 2013) • ICMR National Ethical Guidelines for Biomedical and Health Research Involving Human Participants, 2017 • Good Clinical Practice (GCP) Guidelines — Schedule Y, CDSCO • Clinical Trials Registry of India (CTRI) registration prior to first enrolment • Institutional Ethics Committee (IEC) approval from all participating departments 9.4 Data Protection All patient data anonymized using a unique Study ID. CRFs stored in locked cabinets. Electronic data on password-protected institutional server accessible only to principal and co-investigators. Data retention for 5 years post-publication per ICMR guidelines. 8. STUDY TIMELINE Month Phase Key Activities Month 1–2 Preparation & Ethics IEC submission and approval; CTRI registration; CRF design and piloting; team training in ONSD measurement with inter-observer reliability testing (target ICC > 0.85); standard operating procedures finalized Month 3 Pilot Phase Enroll first 15 patients (5 per group); validate measurement workflow, timing feasibility, data quality; minor protocol adjustments if required Month 4–8 Main Enrolment — Block 1 Enroll patients consecutively to all three groups; target 15–18 patients/month across all procedures; monthly data quality checks; bi-monthly PI meetings Month 9–11 Main Enrolment — Block 2 Complete target of 150 patients; address dropouts or conversions; ensure 10 suspect patients per group enrolled; additional ONSD at T6 (24h) for all suspects and obese patients Month 11 (last 2 weeks) Data Lock Database finalized; data cleaning and query resolution; anonymization; statistical datasets prepared Month 12 Analysis & Writing Full statistical analysis; tables and figures; draft manuscript; internal review; submission to target journal 10. EXPECTED OUTCOMES AND SIGNIFICANCE 10.1 Expected Primary Findings Based on available evidence, we predict a statistically significant gradient of IOP and ONSD elevation across the three procedure groups, with Group B (Laparoscopic Appendectomy — Trendelenburg) showing the greatest absolute rise, followed by Group A (LC — reverse Trendelenburg), with Group C (TAPP/TEP — modified Trendelenburg) potentially showing the least significant change — consistent with the prior hernia repair study. This gradient will for the first time provide Indian data to risk-stratify laparoscopic procedures by ocular safety profile 10.2 Expected Subgroup Findings In the 30 glaucoma suspects, we hypothesize: (a) greater absolute IOP rise in all three procedure groups compared to non-suspects; (b) delayed recovery of IOP to baseline in the post-operative period; (c) ONSD remaining elevated beyond 8 hours in obese suspects, consistent with published data showing non-recovery of ONSD at 24 hours in obese laparoscopic patients. These findings would provide the first Indian evidence base for risk-stratified intraoperative IOP monitoring in glaucoma suspects undergoing laparoscopic surgery. 10.3 Clinical Impact and Recommendations This study's output has the potential to generate a formal clinical recommendation — that all patients scheduled for elective laparoscopic abdominal surgery should undergo basic pre-operative ophthalmic screening (IOP + CDR + Van Herick) as part of the standard pre-anaesthetic evaluation, analogous to cardiorespiratory assessment. For identified glaucoma suspects, the study provides data to support: (1) pre-operative IOP optimization; (2) use of low-pressure pneumoperitoneum where feasible; (3) intraoperative IOP monitoring; and (4) mandatory post-operative ophthalmology review within 24 hours. These are zero-cost, evidence-driven interventions that could prevent POVL. 10.4 Publication Potential The multi-procedure, multi-department, simultaneous IOP+ONSD prospective design with a glaucoma suspect subgroup is methodologically superior to all previous single-procedure Indian studies. Target journals: Indian Journal of Ophthalmology, Surgical Endoscopy, Journal of Laparoendoscopic and Advanced Surgical Techniques, Cureus (open access). Conference presentations: IAGES, DOS, ISAKOS India. This study is also suitable as a thesis topic for MS (General Surgery) or MS (Ophthalmology) with joint departmental supervision. 11. TEAM, EQUIPMENT AND BUDGET Role Department Responsibility Principal Investigator General Surgery Overall coordination; patient recruitment for Groups A, B, C; surgical standardization Co-Investigator 1 Ophthalmology Pre-operative screening; IOP and ONSD measurements at all time points; glaucoma suspect classification and follow-up Co-Investigator 2 Anaesthesiology GA administration per institutional protocol; haemodynamic parameter recording; EtCO₂ and anaesthetic agent documentation at each time point PG Resident / Research Associate General Surgery or Ophthalmology CRF data entry; patient scheduling; T5/T6 follow-up measurements Biostatistician Community Medicine / External Consultant Sample size, analysis plan, SPSS/Prism analysis, manuscript tables Equipment Availability Use in Study Non-contact tonometer (NCT / air-puff) Ophthalmology OPD — available T0, T5, T6 — awake patient; no topical anaesthesia needed Tono-Pen AVIA applanation tonometer Ophthalmology OPD / OT — available T1–T4 — intraoperative under GA; applied to conjunctiva 7.5–10 MHz linear ultrasound probe Radiology / Emergency — available ONSD at all time points; sterile probe cover required Slit-lamp with 90D lens Ophthalmology OPD — available Van Herick grading + CDR at T0 Standard laparoscopic stack OT — available No additional requirement Standard GA agents (inhalational/IV) Hospital pharmacy — available Recorded as covariate; not mandated Sterile ultrasound probe covers Procure — consumable ~Rs. 150–200 per case × 150 = Rs. 22,500–30,000 Budget Item Estimated Cost (INR) Sterile probe covers (150 cases × Rs.200) Rs. 30,000 Ultrasound gel (bulk supply) Rs. 3,000 Printed CRFs, stationery, files Rs. 5,000 Statistical software / SPSS licence Rs. 8,000–12,000 Institutional Ethics Committee fee Rs. 5,000–10,000 CTRI Registration Free (mandatory, Government portal) Open-access publication fee (Cureus: free; IJOS/Surg Endosc: Rs.0–30,000) Rs. 0–30,000 Miscellaneous (printing, binding, presentations) Rs. 5,000 TOTAL ESTIMATED BUDGET Rs. 56,000 – 95,000

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