The foremost cause of blindness in the world is cataract and cataract surgery is one of the most common procedures done worldwide.1 While phacoemulsification is considered superior than manual small incision cataract surgery (MSICS) in terms of early post-operative recovery and better uncorrected visual acuity (UCVA),2 the cost and the maintenance of the machine is rather high. So, in developing countries where there is a vast backlog of cataract surgeries, MSICS is preferred due to its low cost3 and safety in challenging situations like hard cataract,4 phacolytic5 and phacomorphic glaucoma.6
Though in MSICS, a rigid intraocular lens (IOL) is implanted at an reasonable cost, it has high rates of posterior capsular opacification (PCO)7,8 which can lead to decreased vision increasing the burden on the patient both visually and monetarily. Besides, Nd:YAG laser capsulotomy for treating PCO has its own complications like raised intraocular pressure, vitreous prolapse, retinal detachment among others.9 To circumvent these difficulties for the people coming from humble background some of whom even avoid the follow up visits due to absence of awareness or travel difficulties, we can deliver the advantages of a foldable IOL with its sharp optic edge which reduces the migration of lens epithelial cells thereby decreasing the rate of PCO. Singh et al advises that in MSICS where the incision size is less than 5mm, foldable IOLs can be implanted.10
The perfect cases for in-the-bag implantation of a single piece foldable IOL are immature cataract with nuclear sclerosis less than grade 4 and soft mature cataract as in these cases we can keep the sclerocorneal incision size within 6mm and the nucleus can be removed easily through a 5-5.5mm capsulorrhexis which will provide a 360 degree optic margin overlap which is a criterion for preventing PCO. In hard cataracts or in intumescent mature cataracts where we occasionally need large external incision and capsulorrhexis, in-the-bag IOL implantation and optic margin overlap is not always guaranteed. Chang et al confirmed that there is incidence of late onset secondary pigmentary glaucoma on implantation of foldable IOL in the sulcus.11 Hence, placing of single piece foldable IOL in sulcus should be avoided.
If the integrity of the capsulorrhexis is compromised, an effort to place a single piece foldable IOL in the bag may cause the anterior capsular tear to extend into the posterior capsule. In such cases, it is advisable to place a 3-piece IOL either in the bag or the sulcus. The C loop haptics of the multipiece acrylic foldable IOL improve stabilization at the sulcus and apply even tension to the adjacent tissues.12 The higher refractive index of the acrylic materials makes the optic thinner.13 So, there is more distance between the IOL and the posterior surface of the iris which reduces the chances of iris chaffing and pigment dispersion. A variation would be to implant the IOL with the haptics in the sulcus while the optic is captured into the bag. This simulates in-the-bag IOL implantation.
In conclusion, foldable IOL can be implanted in MSICS in particular cases and the rates of decreased PCO with foldable IOL can offer patients with prolonged good visual outcome and better satisfaction.
References
1. Micieli JA, Arshinoff SA. Cataract surgery. CMAJ 2011;183(14):1621.
2. Riaz Y, de Silva SR, Evans JR. Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus phacoemulsification with posterior chamber intraocular lens for age-related cataract. Cochrane Database Syst Rev 2013;(10):CD008813.
3. Gogate P, Deshpande M, Nirmalan PK. Why do phacoemulsification? Manual small-incision cataract surgery is almost as effective, but less expensive. Ophthalmology 2007;114(5):965-8.
4. Venkatesh R, Tan CS, Singh GP, Veena K, Krishnan KT, Ravindran RD. Safety and efficacy of manual small incision cataract surgery for brunescent and black cataracts. Eye (Lond) 2009;23(5):1155-7.
5. Venkatesh R, Tan CS, Kumar TT, Ravindran RD. Safety and efficacy of manual small incision cataract surgery for phacolytic glaucoma. Br J Ophthalmol 2007;91(3):279-81.
6. Ramakrishanan R, Maheshwari D, Kader MA, Singh R, Pawar N, Bharathi MJ. Visual prognosis, intraocular pressure control and complications in phacomorphic glaucoma following manual small incision cataract surgery. Indian J Ophthalmol 2010;58:303-6.
7. Cheng JW, Wei RL, Cai JP, Xi GL, Zhu H, Li Y, Ma XY. Efficacy of different intraocular lens materials and optic edge designs in preventing posterior capsular opacification: a meta-analysis. Am J Ophthalmol 2007;143(3):428-36.
8. Hennig A, Puri LR, Sharma H, Evans JR, Yorston D. Foldable vs rigid lenses after phacoemulsification for cataract surgery: a randomised controlledtrial. Eye 2014;28(5):567-75.
9. Murrill CA, Stanfield DL, van Brocklin MD. Capsulotomy. Optom Clin 1995;4:69-83.
10. Singh K, Misbah A, Saluja P,Singh AK. Review of manual small-incision cataract surgery. Indian J Ophthalmol 2017;65:1281-8.
11. Chang SH, Wu WC, Wu SC. Late-onset secondary pigmentary glaucoma following foldable intraocular lenses implantation in the ciliary sulcus: a long-term follow-up study. BMC Ophthalmol 2013;13:22.
12. Brazitikos PD, Balidis MO, Tranos P, Androudi S, Papadopoulos NT, Tsinopoulos IT, Karabatakis V, Stangos NT. Sulcus implantation of a 3-piece, 6.0 mm optic, hydrophobic foldable acrylic intraocular lens in phacoemulsification complicated by posterior capsule rupture. J Cataract Refract Surg 2002;28(9):1618-22.
13. Mengual E, Garcı´a J, Elvira JC, Hueso JR. Clinical results of AcrySof intraocular lens implantation. J Cataract Refract Surg 1998;24:114-7.
By,
Dr Manas Nath,
Consultant Cataract, Glaucoma and Refractive Services,
ASG Eye hospital,
BT Road, Kolkata
drmanasnath@gmail.com