Penetrating keratoplasty

Corneal scarring that affects vision is best treated with penetrating keratoplasty. Penetrating keratoplasty generally is considered to have a poor outcome after HZO because of recurrent or chronic inflammation, vascularization, glaucoma, and poor tear film quality. The chances of success seem to improve, however, if the corneal surfece is protected after surgery by lubricants, therapeutic lenses, or tarsorrhaphy or if there has been a long interval since the previous occurrence. 

Bramsen, T, Ehlers, N. Early postoperative changes in graft thickness after penetrating keratoplasty. Influence of host corneal disorder on time course. Acta Ophthalmol (Copenh) 57(2), 258-268 (1979)... 

Theng, J.T, Tan, D.T Combined penetrating keratoplasty and hmbal allograft transplantation for severe corneal burns. Ophthalmic Surg Lasers 28, 765-768 (1997)... 

Sangwan, V.S., Matalia, H.P., Vemuganti, G.K., et al. Early results of penetrating keratoplasty after cultivated limbal epithelium transplantation. Arch Ophthalmol 123, 334-340 (2005)... 

Bullous keratopathy is a major complication of cataract surgery. In the past, penetrating keratoplasty was considered the most effective therapy for the symptomatic stage of the disease. Other surgical options have included conjunctival flaps, enucleation (reserved for blind, painful eyes) and, more recently, deep phototherapeutic keratectomy and amniotic membrane transplantation. Medical therapy of bullous keratopathy using hypertonic saline (Nad 5%) has been of marginal benefit due to its relatively weak osmotic effect. 

Van der Veen, G., Broersma, L., Van Rooijen, N., et al. (1998), Cytotoxic T lymphocytes and antibodies after orthotropic penetrating keratoplasty in rats treated with dichloromethylene diphosphonate encapsulated liposomes, Curr. Eye Res., 17, 1018-1026. 

Javadi, M., Yazdani, S., Kanavi, M., Mohammadpour, M., Baradaran-Rafiee, A., Jafarinasab, M., Einollahi, B., Karimian, F., Zare, M., Naderi, M., Rabei, H. (2007). Long-term outcomes of penetrating keratoplasty in chronic and delayed mustard gas keratitis. Cornea 26 1074-8. 

Snyder RW, Sherman MD,AIIinson RW. Intracameral tissue plasminogen activator for treatment of excessive fibrin response after penetrating keratoplasty. AmJ Ophthalmol lS>90 109 483-484. 

Prophylactic oral acyclovir reduces the likelihood of HSV recurrence after penetrating keratoplasty for herpetic eye disease. 

Borderie VM, Meritet J, Chaumeil C, et al. Culmre-proven herpetic keratitis after penetrating keratoplasty in patient with no previous history of herpes disease. Cornea 2004 23(2) 118-124. 

Van Rooij J, Rijneveld WJ, Remeijer L, et al. Effect of oral acyclovir after penetrating keratoplasty for herpetic keratitis a placebo-controlled multicenter trial. Ophthalmology 2003 110(10) 1916-1919. 

Steroid-indnced calcinm deposits in the cornea have been reported. Patients with such persistent epithelial defects snch as postoperative inflammation, penetrating keratoplasty, and a history of herpetic keratitis and dry eye have developed a calcific band keratopathy after topical nse of a steroid phosphate formnlation. 

To help relieve patient discomfort due to the rupture of epithelial bullae, a therapeutic soft contact lens may be tried. Effective restoration of patient comfort and visual function for well-established Fuchs dystrophy, however, may be best achieved through penetrating keratoplasty (Figure 26-7). Fuchs dystrophy is the primary condition... 

Penetrating keratoplasty may restore functional vision when posttraumatic corneal scars are dense and... 

Patients abusing topical anesthetics such as tetracaine and proparacaine will likely conceal the use of the anesthetic and will repeatedly deny anesthetic use even after extensive treatment, such as a penetrating keratoplasty. Patients typically have a history of a corneal injury that... 

If topical anesthetic abuse is suspected, discontinuation is critical. A broad-spectrum topical antibiotic such as 0.5% moxifloxacin three times daily is used to protect the disrupted corneal epithelium from secondary infection as the tissue heals. Topical NSAIDs, such as 0.1% diclofenac sodium solution or 0.5% ketorolac solution, and a therapeutic soft contact lens help to reduce pain. Cycloplegic and topical steroids are indicated if an anterior chamber reaction is present.Toxic keratitis can heal without permanent vision loss within days after discontinuing the use of the anesthetic but may result in permanent scarring, vascularization, and visual loss. Surgical treatment, such as a penetrating keratoplasty, may be necessary. 

The use of steroids is contraindicated in eyes in which there is a threat of perforation, because the steroid negatively affects collagen synthesis. When a penetrating keratoplasty is necessary, steroids may be used up to 24 hours before surgery to lessen postsurgical inflammation and improve the chances of success. 

Herpes simplex keratitis (HSK) is caused by HSV type 1 in adults and is one of the most common infectious etiologies of blindness. It is second only to trauma as a cause of corneal blindness in the United States, where an estimated 50,000 new or recurrent cases are seen each year. Recurrent HSK can be reactivated by many factors in addition to those listed above. Reactivation has been reported in patients after penetrating keratoplasty, argon laser trabeculoplasty, Nd YAG laser peripheral iridotomy, or treatment with excimer lasers, including cases in which ocular herpes had not occurred previously. It is important to realize that because most patients have latent HSV it is possible for a reactivation to occur despite a negative history of a primary infection. 

Generally, necrotizing IK should be treated in the same manner as disciform keratitis, but necrotizing keratitis is much less responsive to steroids.As with disciform keratitis, the steroid must be tapered very slowly, often over a period of months or years. Conjunctival flaps may be necessary as may temporary or permanent tarsorrhaphy, and penetrating keratoplasty. 

Penetrating keratoplasty may be needed after pharmacotherapy if a visually debilitating corneal scar remains. The use of keratoplasty as a therapy for Acanthamoeba keratitis that is not responding to medical therapy is a subject of debate. It is preferable to perform the surgery when active inflammation is not present, and recurrence appears to be common if it is... 

Goegebuer A, Ajay L, Claerhout 1, et al. Resmts of penetrating keratoplasty in syphihtic interstitial keratitis. BuU Coc Beige Ophthalmol 2003 290 35-39... 

Epithelial and stromal edema of the cornea and a diffuse bullous keratopathy developed in a 39-year-old woman 2 weeks after a preoperative disinfection of the face with an alcoholic chlorhexidine solution. This led to penetrating keratoplasty 10 months later (20). 

Grossniklaus H.E., Waring, G.O., 4th, Akor, C., Castellano-Sanchez, A. A. and Bennett, K, 2003, Evaluation of hematoxylin and eosin and special stains for the detection of acanthamoeba keratitis in penetrating keratoplasties. American. Journal of Ophthalmology 136, 520-526. 

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