Anatomy of SCLERA

APPLIED ANATOMY OF SCLERA

Sclera forms the posterior five-sixth opaque part of the external fibrous tunic of the eyeball. Its whole outer surface is covered by Tenon's capsule. In the anterior part it is also covered by bulbar conjunctiva. Its inner surface lies in contact with choroid with a potential suprachoroidal space in

KERATOPLASTY

Keratoplasty, also called corneal grafting or corneal transplantation, is an operation in which the patient's diseased cornea is replaced by the donor's healthy

VASCULARIZATION OF CORNEA

Normal cornea is avascular except for small capillary loops which are present in the periphery for about 1 mm. In pathological states, it can be invaded by
vessels as a defence mechanism against the disease or injury. However, vascularization interferes with corneal

Refractive surgery for astigmatism

Refractive surgical techniques employed for myopia
can be adapted to correct astigmatism alone or
simultaneously with myopia as follows:
1. Astigmatic keratotomy (AK) refers to making
transverse cuts in the mid periphery of the steep
corneal meridian (Fig. 1).

Fig. 1. Astigmatic keratotomy. (A) showing flat and deep meridians of cornea; (B) paired transverse incisions to flattern
the steep meridian; (C) showing correction of astigmatism after astigmatic keratotomy.

AK can be performed
alone (for astigmatism only) or along with RK (for
associated myopia).
2. Photo-astigmatic refractive keratotomy (PARK)
is performed using 

Refractive surgery of myopia

Surgery to correct refractive errors has become very
popular. It should be performed after the error has
stabilized; preferably after 20 years of age.

Refractive surgery of myopia
1. Radial keratotomy (RK) refers to making deep (90 percent of corneal thickness) radial incisions in the peripheral part of cornea leaving the central 4 mm optical zone (Fig 1).

Fig. 1. Radial keratotomy. (A) configuration of radial
incisions; (B) depth of incision.

These incisions on healing; flatten the central cornea thereby reducing its
refractive power. This procedure gives very good correction in low to moderate myopia (2 to 6 D).

Disadvantages. Note: Because of its disadvantages
RK is not recommended presently. (i) Cornea is
weakened, so chances of globe rupture following
trauma are