The Cathedral Eye Clinic

What is keratoconus?

Keratoconus is a non-inflammatory, progressive disorder of the cornea. The cornea is the transparent front surface of the eye that provides most of the eyes optical power. Together with the lens, the cornea refracts light, and as a result helps the eye to focus. With keratoconus, the cornea becomes thinner and irregular in shape. The diseased area bulges outwards causing an increase in myopia (short-sightedness) and astigmatism (abnormal corneal curvature) leading to poor vision. Symptoms include blurred vision, distortion, glare and possibly double vision. Frequent changes in spectacle prescription may be noticed. Keratoconus usually starts around puberty with a slow progression; however the rate of progression varies between patients. It usually affects both eyes but one eye may be affected more than the other.

How is it diagnosed?

Most cases of keratoconus are detected during an eye examination. There are visible signs in the cornea and these can be seen with a slit-lamp (a type of microscope). A scan of the eye with a corneal topographer (a device that measures the curvature of the cornea) is often used in the diagnosis of the disease and to monitor the disease progression.

How many people are affected?

Keratoconus is a rare condition. The number of patients affected varies between 1 in 3,000 and 1 in 10,000 depending on geographic location.

What causes keratoconus?

The cause is unknown. However keratoconus has both systemic and ocular associations. Some of the systemic associations include Downs, Turner, Ehlers-Danlos and Marfan syndromes, atopy, osteogenesis imperfecta and mitral valve prolapse. Ocular associations include vernal keratoconjunctivitis, blue sclera, aniridia, ectopia lentis, Leber congenital amaurosis and retinitis pigmentosa.

What are the treatments available?

• Spectacles and soft contact lenses:
  At the very early stages of the condition, spectacles or soft contact lenses may correct the induced myopia and astigmatism. However small changes in the disease will have a dramatic effect on your spectacle prescription.
• Rigid contact lenses:
  As the condition progresses and the cornea continues to thin and change shape, rigid contact lenses can be used to correct the vision more adequately. These contact lenses must be carefully fitted and require frequent checkups. Lens changes may be required to maintain good vision. Unfortunately contact lenses do not stop nor slow the progression of the disease.
• Corneal collagen cross linking with riboflavin (C3-R®):
  The cornea is made of collagen (connective tissue) and in keratoconus the anchors between collagen fibres are weak. This treatment strengthens the collagen structure in the cornea preventing the cornea from bulging out. The treatment is relatively non-invasive and involves application of a custom-made riboflavin eye drop and then exposure of the eye to UV light. The result is increased cross linking of the collagen fibres in the cornea.
• Intrastromal corneal rings (Intacs™):
  Intacs prescription inserts are particularly useful for patients who are contact lens intolerant or to defer the need for corneal graft/transplant surgery. It is a good surgical option as it has a lower rate of complications compared with corneal transplant surgery. The corneal implants are flexible, crescent-shaped rings that are made of PMMA (polymethylmethacrylate). Placement around the periphery (sides) of the cornea causes gentle re-shaping and flattening of the central cornea. The surgical procedure is usually preformed under local anaesthesia but this depends on the patient. There are various implants available with a range of thicknesses for different degrees of correction. An incision is made in the cornea with a special probe or a laser to create a channel and the plastic implants are then inserted into the channels. Some patients may require contact lenses following this surgery; however the tolerance to the lenses should be better. The implants can be removed or exchanged if necessary without affecting the central cornea. The Intacs cannot be felt, are no more visible than a contact lens and require no maintenance. Based on the results of a large scale European study, Intacs received regulatory approval (CE Mark) for use in the treatment of keratoconus. They are supported by more than ten years of clinical studies and have received NICE approval in the UK and FDA approval in the US.
  C3-R treatments can be combined with Intacs to flatten the cornea more so than with Intacs alone. The C3-R treatment aims to stabilize keratoconus from progression and the Intacs reverse the keratoconus steepening that has already occurred.
• Keratoplasty:
  In approximately 10%-20% of keratoconus patients the cornea may become extremely steep, thin and irregular and the vision cannot be improved sufficiently with the above techniques. In these severe cases, a corneal transplant may be required. This is a surgical procedure that replaces the diseased cornea with healthy donor tissue. Where previously keratoplasty was carried out as a full thickness corneal transplant, where possible the endothelial surface is retained and only the anterior (front) surface of the cornea is replaced as a lamellar or deep lamellar graft. Visual recovery after a full thickness transplant takes a long time and complications such as rejection can occur. Lamellar grafts have quicker visual recovery times but with either operation there is a significant possibility that the eye may still need to be fitted with a contact lens.

For more information regarding keratoconus:

UK Keratoconus Self Help and Support Group
The National Keratoconus Foundation
The Keratoconus Center

References:

Mencucci, R., Mazzotta, C., Rossi, F., Ponchietti, C., Pini, R., Baiocchi, S., Caporossi, A. and Menchini, U., 2007. Riboflavin and ultraviolet A collagen crosslinking: in vivo thermographic analysis of the corneal surface. Journal of Cataract & Refractive Surgery, 33 (6), 1005-8. Wollensak, G., Aurich, H., Pham, D.T. and Wirbelauer, C., 2007. Hydration behavior of porcine cornea crosslinked with riboflavin and ultraviolet A. Journal of Cataract & Refractive Surgery, 33 (3), 516-21. Kymionis, G. and Portaliou, D., 2007. Corneal crosslinking with riboflavin and UVA for the treatment of keratoconus. Journal of Cataract & Refractive Surgery, 33 (7), 1143-4. Colin, J., 2006. European clinical evaluation: use of Intacs for the treatment of keratoconus. Journal of Cataract & Refractive Surgery, 32, 747-755. Hustler, A., Manna, A., Morris, S., Obi, A. and Horgan, S., 2007. Intacs for the correction of keratoconus.Journal of Cataract and Refractive Surgery, 33 (8),1354. Rabinowitz, Y.S., 2007. Intacs for keratoconus. Current Opinion in Ophthalmology, 18 (4), 279-283. Kymionis, G.D., Siganos, C.S., Tsiklis, N.S., Anastasakis, A., Yoo, S.H., Pallikaris, A.I., Astyrakakis, N. and Pallikaris, I.G., 2007 Long-term Follow-up of Intacs in Keratoconus. American Journal of Ophthalmology, 143 (2) 236-244. Mohammadpour, M., 2007. Penetrating Keratoplasty for Keratoconus. Ophthalmology, 114 (10) 1952. Paula Grigorian A., 2007. Extended long-term outcomes of penetrating keratoplasty for keratoconus. Evidence-Based Ophthalmology,8 (1) 12-13. Watson SL, Ramsay A, Dart JK, Bunce C, Craig E. Comparison of deep lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus. Ophthalmology. 2004 Sep;111(9):1676-82.

Cataracts result in loss of transparency of the natural clear lens which results in patients finding it increasingly difficult to see. The first sign may be an increased reliance upon reading glasses. These can be removed through a simple quick operation. A choice exists of types of intraocular lenses available to replace the cataract with new types of intraocular lenses.

Intraocular Lens Procedures

An intraocular surgical procedure is used to treat patients who are either not suitable for laser surgery because their refractive error is too great or they have a corneal problem. The two principal types of intraocular procedure include phakic IOL implantation or clear lens extraction.

• Phakic IOLs gain their name on the basis that a person retains their own lens within the eye and these lenses are additional. They can be thought of as implantable contact lenses.
• Clear Lens Extraction is particularly suitable for people over the age of 40 where their natural lens is becoming less flexible and unable to change shape and focus. The procedure is reserved for patients with large refractive errors who are not suitable for laser refractive surgery

Cataract results

In 2007 alone Cathedral Eye Clinic has currently carried out more than 900 cataract operations. The results of these surgeries are constantly being audited with the aim to ensure that results are of the highest standard possible and where possible to fine tune and constantly improve these results.

Postoperative overall visual results of cataract surgery carried out by The Cathedral Eye Clinic demonstrated that greater than 90% of patients resulted in a best corrected vision of 6/12 or better. This compares well with similar studies carried out in the UK with the final visual acuity in some patients very much related to the degree of co-morbidity.

The first column represents the visual results published from the most commonly reported national UK study of cataract results called the National cataract survey published by Desai in the BJO, this represents the visual results from 15787 patients. The second column represents the visual results from 400 consecutive cataract patients treated in 2007 by the Cathedral Eye Clinic in conjunction with 352 medical consulting.

Best Corrected Visual Acuity Post surgery:

UK NCS

Cathedral Eye Clinic / 352
All patients 86% >/= 6/12
92.5%>/=6/12

Desai; P, Minassian DC & Reidy A. National cataract surgery survey 1997−8: a report of the results of the clinical outcomes. Br J Ophthalmol 1999; 83: 1336−1340.

Age related macular degeneration is the leading cause of visual loss in the over 65s in the developed world. As the elderly population increases the incidence of this disease consequently also increases. Various different treatments have been evolving to manage this condition over the years.

• Laser
• Photodynamic therapy
• Surgery
• Anti-VEGF therapies
• Possible nutrient prophylaxis (Age Related Eye Disease Study)

Risk Factors:

• Age
• Smoking
• Genetics
• Gender
• Nutrient status (possibly)

When are treatments for ARMD useful?

Laser, Photodynamic therapy, Surgery and anti-VEGF therapies are only useful when choroidal neovascularisation has occurred. The process of choroidal neovascularisation occurs when blood vessels accompanied by inflammatory cells grow under and through the retinal pigment epithelium to disrupt and damage the delicate overlying retinal cells.

The tissue invasion is as described above not only new blood vessels but also inflammatory cells. Specific treatments to target either or both of these components are being actively researched. Anti-VEGF treatments principally target the vascular components. Injectable steroids such as triamcinolone target principally the inflammatory cell component This has been termed a two component target therapeutic model for CNV

(Gasparini G, et al. (2005)J Clin Oncol 23:1295-1311)

Cathedral Eye Clinic are currently using both anti-VEGF, intraocular steroids and laser photocoagulation as part of the therapeutic modalities designed to manage these conditions.

Diabetes is very common, affecting approximately 1 in 25 patients in the developed world. In the UK up to 9% of the whole NHS budget is used to treat diabetes and its related complications.

The condition can start in childhood or later in life. It can affect many different parts of the body, but particularly the eye.

How does diabetes affect the eye?

Diabetes can affect the eye in various ways. The most serious effects however are through problems in the retina. This problem is called diabetic retinopathy.

Diabetic retinopathy occurs as a consequence of diabetes and can result in loss of vision either through leaky blood vessels causing swelling of the retina or by causing the production of abnormal blood vessels which result in bleeding within the eye and scaring of the retina.

Screening is essential to detect vision threatening stages prior to loss of vision.

Having diabetes does not mean that a person will have eye problems, but it is important that regular eye examinations are carried out to ensure that any potential problems are diagnosed early. Sight loss from diabetes can usually be prevented if retinopathy is diagnosed and treated early. After diagnosis the condition can be graded by a person’s eye specialist depending on its severity.

Treatment

The most important aspect of management of diabetes is to ensure that good cooperation exists between each patient and the team of health professionals who are involved in managing their care. The general practitioner is key to proper management of all systemic medical factors. However, the ophthalmologist as a diabetic retinopathy screener in addition to directly managing retinal problems should provide support to the GP by helping to communicate the value of good systemic medical management. Strategies for treatment combine optimization of systemic risk factors such as blood glucose control, blood pressure management, reducing blood lipid levels.

Evidence for the value of controlling these factors includes:

Glycaemic Control:- Diabetes Control and Complications Trial (DCCT) demonstrated a 26% reduction in the risk of developing macular oedema where there was intensive insulin treatment

Blood Pressure Control:- UK Prospective Diabetes Study (UKPDS) reported a 47% reduction in loss of vision from macular oedema in Type II diabetics where there was tight blood pressure control

Blood Lipid Control:- The DCCT and the ETDRS studies have demonstrated positive correlations between lipid profiles and the development of macular oedema in patients with type I Diabetes.

Smoking:- This is a well recognized risk factor for diabetic micro- and macrovascular problems. No diabetic should smoke.

Local Ophthalmic Treatment

The Cathedral Eye Clinic follows the Early Treatment of Diabetic Retinopathy Study (ETDRS) guidelines when managing diabetics with laser photocoagulation. This study sponsored by the US National Eye Institute has shown that early laser intervention when clinically significant macular oedema is present can reduce the risk of moderate visual loss by 50%.

In addition to the ETDRS study guidelines the institute advocates using larger spot sizes with longer durations and lower energy profiles. This is in response to more recent studies demonstrating effectiveness of this technique while minimising any side-effects of the laser treatment. (Roider J et al, 2000, BJO 84(1):40-47)

What is glaucoma?

Glaucoma is a disease which results in progressive damage to the optic nerve.

The prevalence of this disease has been estimated through various studies to be in the region of 2% of the population. This rate rises considerably with age so that over the age of 80 greater than 12% of the population may be affected.

Often glaucoma goes undetected until significant visual loss has occurred

What evidence is there that treatment is effective for glaucoma?

1. The early manifest glaucoma treatment study has shown that treatment reduces progression of disease
2. The ocular hypertensive treatment study showed that intra-ocular pressure reduction by 20% decreased the risk of disease progression
3. The advanced glaucoma intervention study showed that lower IOP is associated with reduced progression of visual field loss
4. The collaborative normal tension glaucoma study showed that reducing IOP by 30% reduced glaucoma progression

It is therefore very important to pick up evidence of the disease as early as possible to enable doctors to intervene before significant damage has occurred.

Do you know if you should you be screened for glaucoma?

Please answer these questions:

1. Are you over 40 years of age Yes / No
2. Has anyone in your family ever been diagnosed with glaucoma Yes / No
3. Have you ever been diagnosed with hypertension or diabetes Yes / No
4. Is it more than 2 years since you have had a comprehensive eye test Yes / No
5. If the answer to any of these questions is yes then you should be screened.

What tests will be carried out during screening?

1. Visual acuity is a common ocular test routinely carried out by any ophthalmic practitioner
2. Intra-ocular pressure measurements
3. Visual field testing
4. Optic nerve examination and documentation

Will testing always tell me if I have glaucoma?

Often in the early stages of glaucoma it is not possible to definitively determine the diagnosis. In these cases the importance is that regular follow up occurs and treatment intervention if required

Audit Results From Cathedral Eye Clinic Glaucoma Screening

See below the results / outcomes of our last 47 patients VF results:

What were the outcomes?