Effect Of High Energy Capsulotomy On Aqueous Cytokine Profiles And Pupil Size During Femtosecond Laser-Assisted Cataract Surgery

Standard femtosecond laser energy has been shown to be insufficient to produce a reliable and complete capsulotomy in certain clinical circumstances e.g. in the presence of an ophthalmic viscoelastic device or increased corneal thickness. Increasing laser capsulotomy energy settings improves the reliability of capsulotomy creation in these cases. This study aimed to assess whether aqueous cytokine profiles are altered when high capsulotomy energy was used in eyes undergoing femtosecond laser-assisted cataract surgery (FLACS), and if preoperative use of a topical NSAID had an effect on this.

Prospective study conducted in Singapore National Eye Centre.

This prospective study recruited eighty-three eyes of 63 patients that were allocated to four treatment groups: conventional phacoemulsification (n=20); FLACS, 90% capsulotomy energy without NSAID pretreatment (n=20); FLACS, 90% capsulotomy energy with NSAID pretreatment; FLACS (n=21), 150% capsulotomy energy with NSAID pretreatment (n=22). Topical ketorolac was administered in the groups receiving NSAID pretreatment. FLACS was performed with a low pulse energy femtosecond laser system. Aqueous humour was collected before and after phacoemulsification and cytokine profiles (PGE₂, IFN- γ, IL-6, IL-8, IL-10) were assessed. Pupil size and iris parameters, including iris area and thickness, were measured before and after laser capsulotomy. 

Compared to conventional phacoemulsification, FLACS (90% capsulotomy energy) increased aqueous concentration of PGE₂, IFN-γ and IL-6. However, when increasing capsulotomy energy from 90% to 150%, with the addition of topical NSAID, there was no significant increase in aqueous concentration of PGE₂ (p=0.99), IFN-γ (p=0.99), or IL-6 (p=0.99). For 90% and 150% capsulotomy energy settings, there was a significant decrease in pupil diameter and area following laser capsulotomy. An increase in PGE₂ concentration was correlated with a reduction in pupil area (p<0.001) and diameter (p<0.001). However, when topical NSAID was given preoperatively, there was no difference in the degree of miosis between 90% and 150% capsulotomy energy groups. 

This study is the first to analyse aqueous cytokine profiles for 90% and 150% capsulotomy energy settings in a low pulse energy femtosecond laser system. Pretreatment with topical NSAID prevented a rise in PGE₂, IFN-γ and IL-6 levels and excessive miosis even though a higher capsulotomy energy was used in FLACS. Therefore, when topical NSAIDs are used preoperatively, it is safe to use higher energy settings (with a low pulse energy femtosecond laser system) to achieve a satisfactory capsulotomy.