Cataract remains the leading cause of reversible blindness worldwide, accounting for nearly half of all cases of visual impairment globally.^[1] More than 90% of the visually impaired live in developing countries, where cost-effective, high-volume surgical strategies are essential.^[2] In India alone, approximately five million cataract surgeries are performed each year, making the choice of surgical technique a matter of substantial public health importance.^[3]

Small Incision Cataract Surgery (SICS), performed through a scleral tunnel incision, has emerged as the preferred technique in high-volume settings because it combines the benefits of extracapsular surgery with the advantages of self-sealing wound architecture: reduced astigmatism, rapid visual rehabilitation, machine independence and lower cost.^[4,5] The irrigating vectis technique of nucleus delivery is widely favoured within SICS because of its relative simplicity and gentle handling of the anterior chamber.

The corneal endothelium, a non-regenerating monolayer of hexagonal cells, is responsible for maintaining corneal transparency through its pump-barrier function. Endothelial cell density (ECD) declines naturally with age from approximately 3000–3500 cells/mm² in young adults to 1500–2000 cells/mm² in the elderly.^[6] Any intraocular surgical procedure causes further, irreversible cell loss. When ECD falls below 400–500 cells/mm², the functional reserve is insufficient to maintain corneal deturgescence, resulting in bullous keratopathy.^[7]

Specular microscopy, introduced by Maurice in 1968 and developed for clinical use by Laing in 1975, allows non-invasive quantification of ECD and morphological parameters (pleomorphism, polymegathism) both pre- and postoperatively.^[8] Multiple studies have evaluated endothelial cell loss after SICS, but reported figures vary widely owing to differences in nucleus delivery technique, cataract grade, and inclusion criteria.^[9,10]

The present study was designed to prospectively quantify endothelial cell changes at two postoperative time-points, 1 week and 6 weeks, following SICS performed exclusively by the irrigating vectis technique, in a defined cohort of senile cataract patients with preoperatively normal endothelia.

MATERIALS AND METHODS

Study Design and Setting

This was a prospective observational study conducted at Ahalia Foundation Eye Hospital, Palakkad, Kerala - a JCI-accredited tertiary eye care centre. Patients were recruited consecutively from the outpatient department and surgical camps from January 2012 to November 2012. The study was conducted in accordance with the Declaration of Helsinki and institutional ethical standards; all participants provided written informed consent.

Inclusion and Exclusion Criteria

Patients aged 40 years and above undergoing SICS for senile cataract with a morphologically normal corneal endothelium on specular microscopy were enrolled. Eyes with corneal pathology, pseudoexfoliation, diabetes mellitus, uveitis, glaucoma, vitreoretinal disease, prior intraocular surgery, nuclear sclerosis grade 4 or above (LOCS III), traumatic cataract, or any intraoperative complication such as posterior capsule rent or vitreous loss were excluded.

Surgical Technique

All surgeries were performed by a single experienced surgeon. After peribulbar anaesthesia (5 mL of 2% lidocaine hydrochloride with 1:20,000 adrenaline), a fornix-based conjunctival flap was fashioned at the superior limbus. A 6 mm frown scleral incision was placed 1.5 mm posterior to the limbus; a sclerocorneal tunnel was created with a stainless-steel crescent blade. A side-port was made at 3 or 9 o'clock based on surgeon preference. The anterior chamber was filled with HPMC 2%, and a continuous curvilinear capsulorrhexis (CCC) was created with a 26 G bent needle. An anterior chamber entry was made with a 3.2 mm keratome and extended with an extension blade. Hydrodissection was performed with Ringer's Lactate. After nuclear rotation and delivery into the anterior chamber using a Sinskey hook with OVD support, the nucleus was removed by the irrigating vectis technique. Cortical clean-up was accomplished with a coaxial irrigation-aspiration cannula. A PMMA posterior chamber IOL was implanted in the capsular bag. OVD was meticulously aspirated, and a subconjunctival injection of gentamicin 10 mg and dexamethasone 2 mg was administered.

Endothelial Cell Assessment

Endothelial cell density (cells/mm²) was measured with a Konan Non-Con ROBO Specular Microscope X (NSP-7700) preoperatively and at 1 week and 6 weeks postoperatively. An average of five readings was taken at each visit; the automated cell-counting algorithm supplied by the manufacturer's software was used as the primary analysis method. A variable-frame (manual) count of 50 cells was additionally performed preoperatively and at 6 weeks to corroborate automated findings. Percentage endothelial cell loss was calculated as: [(Preoperative ECD − Postoperative ECD) / Preoperative ECD] × 100.

Statistical Analysis

Data are presented as mean ± standard deviation (SD). The paired Student's t-test was used to compare mean ECD between preoperative baseline and each postoperative time-point. A p-value < 0.05 was considered statistically significant. All analyses were performed using standard statistical software.

RESULTS

Demographic Characteristics

A total of 50 eyes of 50 patients were studied. The mean age was 64.5 years (range 55–75 years). There were 18 males (36%) and 32 females (64%). The majority of patients (21 eyes, 42%) were in the 61–70-year age group, reflecting the peak incidence of senile cataract in this population. Demographic data are summarised in Table 1.

Endothelial Cell Density: Summary Statistics

The mean preoperative ECD was 2688.8 ± 222.2 cells/mm². At 1 week postoperatively, mean ECD was 2556.6 cells/mm², representing a mean loss of 132.2 cells (4.92%). At 6 weeks, mean ECD was 2430.5 ± 283.8 cells/mm² — a mean loss of 258.4 cells (9.61%) from baseline. Summary statistics are presented in Table 2.

Percentage Cell Loss by Time Point

The mean percentage endothelial cell loss at 1 week was 4.92%, increasing to 9.61% at 6 weeks. This pattern is consistent with an early post-surgical inflammatory phase followed by progressive cell loss and remodelling during the first 6 weeks. Table 3 presents percentage cell loss data across both time-points.

Individual Patient Data

Table 4 presents the complete individual patient data for all 50 eyes, including preoperative ECD, 1-week and 6-week postoperative ECD, and cataract morphology.

DISCUSSION

The present study documents a mean endothelial cell loss of 4.92% at 1 week and 9.61% at 6 weeks following SICS using the irrigating vectis technique. These figures are consistent with the range of 4–17% loss reported in the literature for SICS and indicate a clinically acceptable degree of endothelial trauma.^[11]

The pattern of loss observed - with the bulk of cell death occurring within the first week and continued, though slower, loss thereafter - is consistent with the natural history of endothelial injury described by Schultz et al.^[12] Early loss is attributable to direct mechanical trauma from intraocular instrumentation, brief nucleus–endothelium proximity during anterior-chamber manoeuvres, and the acute inflammatory response. Continued cell loss between 1 and 6 weeks may reflect ongoing wound healing, the effects of prolonged postoperative inflammation, or the lag in specular microscopic detection of injured but not immediately lost cells.

Studies employing different nucleus delivery strategies for SICS have reported correspondingly different levels of endothelial loss. Thakur et al. found a loss of 15.83% at 1 month using the same irrigating vectis technique, but included mature and hard cataracts in their series.9 Wright and Chawla reported a 16% loss using the anterior chamber (AC) maintainer technique.^[13] Vajpayee et al. recorded 17.66% at 3 months with the phacofracture approach, and Gogate et al. documented 15.3% at 6 weeks using visco-expression.^[10,14] The lower loss in the present study (9.59% at 6 weeks) is attributable to the exclusion of grade 4 and above cataracts and to the inherent gentleness of the irrigating vectis, which limits the duration of nuclear manipulation within the anterior chamber.

George et al. and Sasikumar et al. reported even lower losses of 6.07% and 4.21% respectively at comparable time-points, both series being restricted to early immature cataracts (NS grades 1–3).^[11,15] The inclusion in the current study of PSC and combined morphologies (NS+PSC, cortical cataract) accounts for the modestly higher mean loss. Harder nuclei require greater intraocular manipulation, generate more mechanical shear at the endothelium, and increase the duration of AC irrigation.

The incremental increase in cell loss between week 1 (4.91%) and week 6 (9.59%) underscores the importance of the 6-week time-point as the minimum follow-up for accurate assessment. Studies with only 1-week follow-up will systematically underestimate the definitive endothelial impact of SICS. The gradual decrease in the rate of loss after 6 weeks, as documented in longer-term studies, suggests that the figures reported here represent near-maximal early loss attributable to the procedure itself.^[8]

Limitations of this study include a sample size of 50 eyes, a relatively short maximum follow-up of 6 weeks, and the absence of morphometric data (coefficient of variation, percentage hexagonality) beyond cell density. A larger study with longer follow-up, including 3- and 12-month assessments and morphometric indices, would provide a more complete characterisation of the endothelial response to SICS.

CONCLUSIONS

SICS using the irrigating vectis technique results in a mean endothelial cell loss of 4.92% at 1 week and 9.61% at 6 weeks postoperatively in patients with senile cataract of up to LOCS III grade 3. This degree of endothelial trauma is clinically acceptable and falls within published ranges for phacoemulsification. The irrigating vectis technique appears to be among the least traumatic nucleus delivery methods for SICS and should be favoured in settings where phacoemulsification is unavailable or cost-prohibitive. A larger, longer-term study incorporating morphometric endothelial parameters is warranted to confirm these findings.

Acknowledgement

I would like to express my sincere gratitude to Dr. Satyajit M V for his invaluable guidance throughout this study. His insightful feedback and expertise were instrumental in shaping this research.

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