The Trabectome device uses high frequency-microelectrocautery with infusion and aspiration simultaneously to ablate the inner wall of the trabeculum and Schlemm’s canal providing direct access for aqueous fluid to collector channels . In 2006, Minckler et al. reported an 84% success rate and high safety profile in a prospective study including 101 eyes over 30 months .
In 2014, Mosaed et al. published a large data pool obtained from the Trabectome Study Group Database, including 5436 patients and 90 months follow-up time . The average IOP reduction was 29% from 23.0 ± 7.9 mmHg to 16.5 ± 3.8 mmHg, and medications were reduced from 2.6 ± 1.3 to 1.6 ± 1.3 (38 %). In the report, the survival rates were 60% for all cases, 76% for combined cases, and 50% for trabectome-only cases. Secondary glaucoma surgery was reported as 7%. A limitation of this report is that it was unclear how many eyes were still included in 90th-month data.
In 2019, Efsandiari et al. reported 5-year outcomes for a combined phacotrabectome case series including 93 patients . In this report, the cumulative probability of success at 5 years was 67.5%. Risk factors for failure were reported as lower baseline IOP, younger age, and higher CCT. Exfoliative glaucoma was associated with a higher success rate. IOP dropped from 20 ± 5.6 to 15.6 ± 4.6 mmHg at 5 years.
In 2019, Avar et al. reported 3.5-year outcomes of 81 trabectome cases, in which IOP decreased by 28% and 26% for POAG and PEX glaucoma, respectively . In the report, the Cox proportional hazard model showed nearly 2 times increased risk of failure in POAG cases compared to PEX glaucoma.
In 2020, Kono et al. published long-term results of 305 trabectome cases, using IOP ≤ 21 mmHg and ≥ 20% reduction as criterion A; IOP ≤ 18 mmHg and ≥ 20% reduction as criterion B; and IOP ≤ 16 mmHg and ≥ 20% reduction criterion as C . Success probabilities for all cases were found as 44%, 35%, and 17% for Criteria A, B, and C, respectively, at 72 months. Baseline IOP dropped from 29.2 ± 9.8 mmHg to 16.4 ± 5.8 mmHg at 72 months. There was no significant difference in success probability at 72 months for glaucoma type in terms of criterion A. On the other hand, the report emphasized that the combined procedure significantly reduced failure risk, whereas POAG and past SLT history significantly increased the failure risk. In this report, it was noted that 44.6% of eyes required subsequent glaucoma surgery.
In our report, we found trabectome was successful in reducing baseline IOP from 26.83 ± 6.5 mmHg to 18.7 ± 4.5 mmHg (p < 0.01) with a mean follow-up of 59 months. The mean IOP decreased by 30.1% and the mean medication quantity decreased from 3.42 ± 0.76 to 2.45 ± 1.33 (p < 0.01). These results are compatible with other reports in the literature.
If we assume surgical success criteria as IOP drop by 20% or IOP ≤ 21 mmHg without additional glaucoma surgery, the success rate was 50% at last visit. During the follow-up period, 24.2% of eyes had additional glaucoma surgery. This is relatively higher than the ratio reported by Mosaed et al., but lower than that of Kono et al. In our report, Kaplan Meier analysis for reoperation time showed mean survival of 69.01 ± 3.5 months (Fig. 1) Cumulative probability of success was 93.5%, 90.5%, 85.5%, 80.6%, and 77.4% at 3, 12, 24, 36, and 60 months, respectively. This is important to see what happens in real life and shows us the benefit of trabectome surgery. This probable success rate is higher than the rate reported by Efsandiari at 5 years which was 67.5% .
Kaplan Meier survival plots indicating the time for additional glaucoma surgery with the subgroups showed higher survival probability with combined surgery and in male patients and lower survival probability in eyes with advanced glaucoma and vitrectomized eyes (Fig. 2). The analysis according to glaucoma types showed better survival for POAG and lower survival for PEX glaucoma and lowest with secondary glaucoma (post-vitrectomy, neovascular, traumatic) at 80 months which seems not to be compatible with the literature. But if the plot is examined in detail, it seems that within the first 25 months, PEX glaucoma had better survival and then the survival probability curve for PEX glaucoma crosses and then declines. In the report by Kono et al. , no significant difference in success probability was found regarding glaucoma type, but in the plot PEX glaucoma had lower survival at 72 months and similarly higher survival at earlier time points. Whereas in the report by Avar et al.  with a mean follow-up of 3.5 years, PEX glaucoma had significantly better survival than POAG. The incompatibility of the reports may be related to the follow-up time as other reports indicating better results for PEX glaucoma had shorter follow-up periods [18–22]. Because PEX glaucoma is associated with fibrillary protein deposition in the trabeculum , it may have a better response to surgeries bypassing trabecular resistance. This may be the reason why early reports had better outcomes for PEX glaucoma.
In our report, multivariate Cox regression analysis showed an increased risk of further surgery with higher baseline IOP (HR:1.12, p:0.01), higher CCT (HR:1.01, p:0.04), and higher number of drugs (HR:2.22, p:0.08). Patients with higher baseline IOP are expected to have higher IOP reduction after trabectome surgery. Many reports found higher baseline IOP was associated with higher IOP reduction after trabectome [15, 24].The data may be biased by the floor effect in normotensive eyes. The higher baseline IOP reflects how aggressive glaucoma is. A recent report published by Kono et al. also found high baseline IOP was associated with a significant increase in failure risk, as in our study .
We observed higher CCT led to increased requirements for further surgery. Efsandiari et al. also reported an association between thicker cornea and risk of failure . Thicker corneas may reflect ultrastructural and biomechanical properties of eyes which may defer more distal outflow facility [25–27].
Limitations of our study are the retrospective design, low patient numbers, and inadequate follow-up data especially in an intermediate period. But the study gives an objective view about the long-term survival after trabectome surgery. Higher baseline IOP, higher drug numbers, higher glaucoma stage, and secondary glaucoma (traumatic, post-vitrectomy, neovascular) reflect the aggressive nature of glaucoma. Combined phacotrabectome was shown to have no additional effect on IOP reduction [24, 28], but it biases patient selection towards the earlier stages .
In conclusion, trabectome surgery achieved 50% success rate at 59 months follow-up. The probability of success was 77.4% if reoperation is a criterion for failure. Higher CCT and higher baseline IOP significantly increase the failure rate in the long term.