**Part 1**

**Penetrating Keratoplasty** 

**1** 

**Clinical Indications for Penetrating** 

**Keratoplasty and Epidemiological** 

**Study in Teaching Hospitals of** 

Mohammad Hossien Davari1 and Hoda Gheytasi2

*Birjand University of Medical Sciences and Health Services, Birjand,* 

The cornea is normally a clear layer of tissue covering the front of the eye, similar to a watch crystal. Its purpose is to refract or bend light rays as they enter the eye, allowing them to

Corneal diseases are a significant cause of visual impairment and blindness in the developing world [3] Penetrating keratoplasty (PK) offers hope for visual rehabilitation in

Corneal transplantation, also known as corneal grafting or penetrating keratoplasty, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue which has been removed from a recently deceased individual having no known diseases which might affect the viability of the donated tissue (1, 4). Corneal transplantation has two major types, penetrating keratoplasty (P.K) in which the full thickness of cornea is replaced and lamellar keratoplasty (L.K) in which a portion of cornea is replaced. The term PK commonly refers to surgical replacement of a portion of the corneal with that of a donor eye. LK surgery consists of placing a partial thickness donor corneal graft in a recipient corneal bed

In Worldwide, Corneal transplant is one of the most common transplant procedures although approximately 100,000 procedures are performed each year; some estimates report that 10,000,000 people are affected by various disorders that would benefit from corneal transplantation. In some situations such as scar, edema, thinning and severe distortion there

The decline of certain disorders due to changes in surgical practice, and the emergence of new surgical techniques have largely influenced the changing trend. The indications for PK have continued to change since 1940 (9-10), and investigators have studied the changing

that is prepared by lamellar dissection of diseased anterior stoma corneal tissue (5, 6).

is no treatment other than corneal transplantation (7, 8).

Indications for corneal transplantation include the following:

trends over the past few decades (9-13).

**1. Introduction**

focus on the retina (1, 2).

many such cases (3).

**Birjand Medical University** 

*2Birjand University of Medical Sciences, Birjand,* 

**from 1999 to 2006** 

*1Vali-Asre Hospital,* 

*Iran* 
