Effect of Hydroxypropyl Methylcellulose (HPMC 2%) as an Adjuvant in Post Chopping the Nucleus in Phacoemulsification Surgery in Hard Cataract on Corneal Outcome

Back ground and rational:

Phacoemulsification cataract surgery plus intraocular ocular lens implantation is a standard of care for the cataract surgery. There are various techniques of phacoemulsification has been described like divide and conquer, stop and chop and direct chop. Before emulsifying the nucleus, the endothelium has to be coated with viscoelastics to protect it from the ultrasonic energy. The usual loss of endothelium after phacoemulsification cataract surgery is estimated to be 5-20% at 1- 3 months . There are some techniques are described like softshell technique i.e., dispersive (HPMC 2%) followed cohesive, sodium hyaluronate 1.4% (NaH) injection to protect the endothelium. We feel that during chopping most of the viscoelastic injected was aspirated during chopping the nucleus and leaving the endothelium less protective form the phaco ultrasonic energy.  There are many studies which compared the different type of viscoelastics like HPMC 2%, Discovisc(hyaluronic acid 1.4% / Chondroitin sulphate 4%), viscoat (Sodium hyaluronate 3% / Chondroitin sulphate 4%)for coating the endothelium but no studies has compared the effect of coating the endothelium with dispersive viscoelastic after chopping the nucleus on the corneal outcome of the phacoemulsification surgery.

Ocular viscoelastic devices (OVD) are very helpful in the cataract surgery. There are various forms of OVDs are available with cohesive property (Sodium hyaluronate 1.4% ) and dispersive property (HPMC2%). Cohesive OVDs are more of solid in nature when injected into the anterior chamber forms the good work place for the intraocular instruments whereas the dispersive OVDs are more of liquid in nature which coats the endothelium better. There are various studies have compared the efficacy of different types of OVDs in the phacoemulsification cataract surgery.Espı´ndola RF et al have compared the efficacy of Discovisc (hyaluronic acid 1.4% / Chondroitin sulphate 4%) with HPMC 2%;  Vajpayee et al have compared Healon GV (Sodium hyaluronate 1.4%) , Healon 5 (Sodium hyaluronate 2.3%), Viscoat (Sodium hyaluronate 3.0% / Chondroitin sulphate 4%); *Maár et al.*compared Healon (Sodium hyaluronate 1%) and Viscoat (Sodium hyaluronate 3% / Chondroitin sulphate 4%); Storr-Paulsen et al have compared the celoftal (HPMC 2%), vitrax (Sodium hyaluronate 3% ) and Healon (Sodium hyaluronate 1%). They have all compared the different type of OVDs before the start of the phacoemulsification.

Novelty/Innovation:

We have realised that some additional dispersive OVDs are needed in the middle of phacoemulsification to coat the endothelium again as most of the OVDs will be aspirated during the initial part of the phacoemulsification. So, we have designed this study to show the efficacy of adjuvant coating of endothelium using HPMC 2% in the middle of the phacoemulsification process i.e., after chopping into multiple pieces and after removing of the half of the nucleus.

Hypothesis/Research question:

1. Is the additional or adjuvant coating of HPMC 2% in the middle of the phacoemulsification helpful for decreasing the corneal oedema and improve the post operative corneal outcome?