Eye Care

“Don’t rub your eyes!” your mother used to say. “It’s not good for you”. But then who ever listened to their mother? It seems that in recent years, science have caught up with our mothers’ wisdom and a number of research papers are now clearly proving that rubbing your eyes can in fact damage your eye’s corneal health.

In our own practice we have seen many cases of keratoconus and healthy corneas distorted due to vigorous rubbing of the eye. The picture below shows the topography of an otherwise normal cornea that is chronically rubbed at the 6 o’clock position. The patient had best corrected vision of about 6/75 (20/25) at the time. Once her allergies were managed and she stopped rubbing the cornea her vision returned back to a normal 6/6 (20/20) after about 2 months.

Back in 1976, Karseras and Ruben wrote in their paper on the aetiology of Keratoconus that most keratoconus patients rub their eyes excessively. Eye-rubbing is considered the dominant aetiological factor in two-thirds of patients with keratoconus who progress to contact lens wear. Charles McMonnies in 2007 seemed to agree that abnormal rubbing may increase the likelihood of the development of some forms of keratoconus. He postulated that when vigorous knuckle-rubbing forces are located on the normal peripheral cornea, the thinner or weakened cone apex may be exposed to high intraocular pressure distending forces that may tend to promote ectasia.

Most recently Dr Alan Carlson wrote a comprehensive article on the dangers of rubbing the eye in patients with Keratoconus and post-LASIK:

Eye care has seen a massive explosion of new diagnostic instruments and treatment procedures in the last number of years.  From instruments like the front and back chamber OCTs, Oculus Pentacam and Zeiss GDx to procedures like Intra ocular injections to halt the progression of previously untreatable wet macular degeneration, 30 days continues wear silicone soft contact lenses, Orthokeratology and also Corneal Collagen Cross-linking (CxL).

People who have Keratoconus are particular excited about the possibility of having Corneal Cross-linking done to their eyes in the hope of improving their sight.  It is however very important to stress that CxL is not a cure for keratoconus.  The main function of the procedure is only to halt the progression of the ectasia (bulge or cone on the cornea).  A couple of months after the procedure some flattening of the cone can occur, but this is not significant enough for the keratoconus patient to have normal sight without the use of other optical devices like Rigid Gas Permeable contact lenses.

For this reason it is not a necessity for all Keratoconus patients to have the Corneal Collagen Cross-linking procedure.  The keratoconus group that will benefit the most from CxL is the ones who develop keratoconus at a young age, normally between the ages of 16 to 28, and show quick thinning and progression of the keratoconus cone. 

Corneal collagen Cross-linking has been available in South Africa for a while but has only recently become available in the United States and Drs James Owen and William Tullo wrote a comprehensive article about CxL for the August edition of the US based Contact Lens Spectrum titled:

A Closer Look at Corneal Cross-Linking

The first treatment to halt the progression of corneal ectasia may soon be available in the United States. Although corneal collagen cross-linking (CXL) is currently available in most countries around the world, the majority of patients in the United States who have keratoconus must wait to access this technology. This procedure is exciting because it will allow for successful contact lens fitting of patients who might otherwise become contact lens intolerant.

I have written before on the age of merging electronics and man (Bionics).  It would seem that science is forever creeping closer to that elusive dream of 'growing' human parts.  Scientist published this article in Sci Transl Med 25 August 2010: Vol. 2, Issue 46, p. 46 reporting on the possibility of implanting biosynthetic corneas.

For all out patients out there desperately waiting for donor corneas this might be a sight saver and I'm sure we will here a lot more about in the future.

The title of the study is 'A Biosynthetic Alternative to Human Donor Tissue for Inducing Corneal Regeneration: 24-Month Follow-Up of a Phase 1 Clinical Study' and the authors were:

One of the most common visual side effects of Post LASIK patients is halo's and ghosting which is more pronounced during low light levels. These visual disturbances are called higher order aberrations (HOA).   In the opinion of contact lens fitters, many patients find relief of the higher order aberrations and improvement of their visual acuity when they wear Rigid Gas Permeable (RGP) lens fitted over the Laser treated corneal area. 

I recently read this research paper titled 'Changes in wave-front aberrations after rigid gas permeable contact lens fitting in post-laser in situ keratomileusis patients with visual complaints' published in Can J Ophthalmol. 2010 Jun;45(3):264-8.

The authors were Tan G, Yang J, Chen X, He H, Zhong X

Intrastromal rings or Intacs broke into the ophthalmic market with a big bang and was hailed as a savior surgical procedure for Keratoconus patients.  The idea is to implant two semi circular rings into the tissue of the cornea on opposite sides of the keratoconus ectasia (protrusion of corneal tissue).  The mechanical effect of the Intact rings is to stretch the corneal tissue and in the process flatten the ectasia point of the Keratoconus.

Unfortunately the surgery outcome of the Intrastromal rings hasn't been as good as expected and very few patients achieve normal functional sight after the procedure.  Another complication is post op infections of the procedure as highlighted on this case study.

A 20-year-old woman presented with photophobia, decreased vision, and pain 11 days after uncomplicated implantation of intrastromal corneal ring segments (ICRSs) for keratoconus in both eyes. Bilateral corneal stromal infiltrates were noted at the site of ICRSs implantation. The patient was started on frequent topical fortified antibiotics in both eyes. Despite aggressive medical management, stromal infiltrates progressed, necessitating removal of ICRSs from both corneas to control infectious keratitis and melting of cornea.

Cultures obtained at the time of initial presentation yielded Streptococcus viridans. Patient responded well to the treatment and was left with stromal scars in both corneas.