Advanced-technology intraocular lenses (ATIOLs), which include aspheric IOLs, toric IOLs, multifocal IOLs (MFIOLs), and accommodative IOLs, have made a paradigm shift in the management of cataract. The innovations and technological advances in this field have made cataract surgery a truly refractive surgery. Newer IOL technologies including trifocal, quadrifocal, and extended depth-of-focus (EDOF) lenses have been instrumental in providing spectacle-free vision at all distances, along with improvement in optics and aberration profiles.

Preoperative workup of a patient opting for an AT IOL starts with a thorough medical history of the patient. The examination begins with the visual acuity and refraction for distance as well as near, followed by intraocular pressure measurement. Schirmer's test and contrast sensitivity test are also done. The patient is then referred to an anterior-segment specialist for a thorough examination of the anterior segment on slit lamp. This includes the adnexa (lids, lacrimal system, etc.), cornea and anterior chamber, and pupils. After full dilation, grading of the cataract is again done by the anterior-segment specialist, followed by a dilated refraction. The patient is next sent to a retina specialist, for a thorough examination of the retina up to the ora serrate. Tests for any posterior-segment findings are conducted, and post cataract visual potential can be prognosticated. A possible need of retinal intervention after cataract surgery is noted. Macular pathology can be one of the limiting factors for determining a patient's inclusion or exclusion for MFIOL implantation. Therefore, detecting macular pathology before cataract surgery is a must. All patients opting for ATIOLs undergo macular optical coherence tomography.

Accommodative IOLS

Partially accommodating IOLs rely on changes in axial position of the IOL. Single-optic IOLs such as Crystalens (B&L), 1CU IOL (HumanOptics), Tetraflex (Lenstec) as well as dual-optic IOLs such as Synchrony (AMO) give antero-posterior movement said to give some degree of both near and distant vision. Synchrony Vu has a central blended aspheric zone to extend depth of focus.

Accommodative IOLs remain the holy grail of ophthalmic surgery. Several options now available are getting closer to the goal of restoring accommodative vision. Some of these act by various mechanisms, including changing optic shape, curvature or thickness to change focus. In-the-bag accommodative IOLs are an interesting innovation. The FluidVision (PowerVision) changes accommodative power by increasing and decreasing the quantity of fluid within the optic.

The Sapphire IOL (Elenza) is electronically controlled, remotely programmable, customisable and utilises nanotechnology, artificial intelligence and advanced electronics to auto-adjust focus in response to pupillary changes. Speed and amplitude of pupillary responses are used to differentiate between light and accommodation.

Special Function IOLS

• Tecnis toric, Symfony toric, Trulign, Lentis toric, enVista, Acrysof IQ and Acrysof IQ ReSTOR multifocal toric are some of the choices available for astigmatism correction. Adjustable IOLS allow postoperative adjustments.
• Light Adjustable Lens (LAL – Calhoun Vision) is a silicone IOL containing light-sensitive macromers that are modified post-operatively using a digital light delivery device to attain desired refraction. UV-protective glasses are worn till changes are finally locked in by re-irradiation.
• Refractive indexing utilises the femtosecond laser to create patterns in the IOL, thereby correcting myopia, hyperopia, astigmatism and higher-order aberrations. It also gives the ability to create specific focal patterns in the IOL.
• Multi-component IOLs allow adjustability by changing the optic component alone while the base component remains fixed, e.g. Precisight (IVO) and Harmoni (ClarVista Medical).
• Piggyback IOLs are available for primary or secondary implantation. Piggyback aspheric, multifocals, torics, negative dysphotopsia (ND) and Age related Macular Degeneration (AMD) IOLs are available. Some examples are Clariflex (AMO), Sulcoflex (Rayner) and AQ5010.

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Journal of Clinical and Experimental Ophthalmology

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