Indications

This procedure can be a single or an additive procedure in KC patients; the following are suggestions for treatment:

Ð When the case is stable and there is high refractive error (> −6 dpt S.E) and BSCVA is reasonable, it can be a single procedure.

ÐWhen the case is stable and there is high refractive error (> −6 dpt S.E) and BSCVA is unreasonable because of high corneal irregularities, it can be an additive procedure in combination with ICRs.

ÐWhen the case is unstable and there is high refractive error (> −6 dpt S.E) and BSCVA is reasonable, it can be an additive procedure in combination with CXL.

ÐWhen the case is unstable and there is high refractive error (> −6 dpt S.E) and BSCVA is unreasonable, it can be an additive procedure in combination with ICRs and CXL.

Table 3.1 summarizes the above guidelines. The above guidelines are general and other guidelines should be considered such as corneal thickness, K-readings, etc.

Conditions

(a)The anterior chamber depth (ACD) measured from the endothelium must be at least 2.8 mm.

(b)Stable refraction.

Contraindications

(a)ACD <2.8

(b)Myopia other than axial

(c)Evidence of nuclear sclerosis or developing cataract

(d)History of uveitis

(e)Presence of anterior or posterior synechiae

(f)Corneal dystrophy

(g)Glaucoma or IOP higher than 20 mmHg

(h)Any other pathology in the anterior segment

(i)Personal or family history of retinal detachment

(j)Diabetes mellitus

Some of the above contraindications depend on the discretion of the surgeon and the needs of the patients.

Relative contraindications include the following:

(a)The patient should not rub the eye. Patients who cannot follow these instructions should not be implanted with a phakic IOL.

(b)The smallest available posterior chamber phakic lens is of 11-mm total diameter. The total diameter

Table 3.1 Guidelines for managing KC with IORLs

of the lens is calculated by adding 0.5 mm to the white-to-white limbal diameter. The minimum white-to-white diameter should be 11 mm. Any degree of microcornea from this size is a contraindication. In the case of an iris claw lens, it is possible to have customized, smaller lenses. While the normal phakic lens is 8.5 mm wide, the iris claw lens may be made as small as 6 mm, thus greatly extending its application.

Considerations

Ophthalmic Examination

All patients should undergo a complete ophthalmic examination:

(a)Manifest and cycloplegic refraction

(b)Uncorrected visual acuity

(c)Spectacle and/or contact lens corrected visual acuity

(d)Slit lamp examination of the anterior segment and ocular adnexa

(e)IOP

(f)Pupil size measurement under scotopic conditions

(g)Corneal endothelial cell count with specular endothelial microscopy

(h)Biometry to calculate axial length of the eyeball and the anterior chamber

(i)White-to-white corneal diameter measurement, if contemplating angle-supported or posterior chamber implants

(j)Videokeratography and keratometry

(k)Fundus examination by indirect ophthalmoscopy

(l)Anatomical imaging by anterior OCT or UBM.

Basic Concepts

When planning for an IORL implant, the surgeon should answer the following questions:

(a)What is the minimum age at which the lens is to be implanted?

(b)What is the minimum or the maximum refractive error to be treated?