- On 21 November 2017
Cataract is opacification of lens substance or capsule with variable lessening of vision. Before considering this disease in detail lets go through eye anatomy in brief.
The optic system of eye is represented by cornea, lens and vitreous humor. Their total refractive power is approximately 60.0 diopter, from which 20.0 diopter provided by lens at resting conditions.
Corneal layer is the transparent part of the front eyeball, light rays pass through cornea, lens and then focus on the retina.
Lens is biconvex transparent body with changing convexity.
Behind cornea and in front of lens there is iris, which contains radially and circularly arranged smooth muscles (sphincter and dilator), which contractions change the pupil size (pupil is the hole in the iris). Via pupil size the amount of the light rays that can be focused on the retina can be regulated.
Vitreous humor is transparent jelly like mass, which fills eye-ball cavity behind the lens. It provides free passage of light rays to the retina.
Retina is the inner layer of an eye, containing photosensitive cells: cones and rods. Cones are for color vision and rods provide night vision.
The yellow spot (macula) is the most sensitive part of the retina, with the highest visual acuity.
Optic disk is localized on the eye fundus, it represents the origin of the optic nerve. Via optic disk information received in cones and rods is transferred to the brain. Optic disc is also called as a “blind spot”.
As we have already mentioned cataract is opacification of the lens, it can be caused by: influence of metabolic disturbances, toxic substances, radiation, congenital anomalies, eye trauma, intraocular inflammatory processes and other factors.
The symptoms and course of the disease varies. Are differentiated congenital and acquired, progressive and non-progressive forms of the disease.
The lens substance consists of proteins and water mainly, protein denaturation causes lens opacification and reduces transfer of light rays to the retina therefore reducing visual acuity. At the initial stages of the disease, subtle lens opacities can be discovered by testing transference of light rays and by bio-microscopy. At the more advanced stages area of pupil become grayish.
Loss of visual acuity depends on the intensity of lens opacification. In case of total loss of lens transparence light can be felt only in right projection (in case of uninjured fundus).
There are surgical and medication treatment options for cataract. Nowadays therapeutic medication Cataxol (World Medicine, England) is widely used for treatment of cataract.
Cataxol eye drops protect lens proteins’ sulfhydril groups from oxidation and also promote dissociation of translucent proteins. Cataxol also increase proteolytic activity of aqueous humor enzymes. Cataxol is especially effective for prophylaxis of the progressive forms of the disease.
In case when therapeutic medications are no more efficient, surgical measures are considered.
As a post surgical prognostic factor, evaluation of the retinal integrity and optic disk viability is crucial.
Often due to lens opacity fundoscopy can’t be provided appropriately. The results of cataract extraction (so called cataract operation) can’t be always beneficial during various disorders, for example during diabetes serious changes take place on the retina known as “diabetic retinopathy”. Even in such case surgery is very important because visual acuity will increase because extraction of opacified material and in addition after extraction physician can dynamically monitor changes that take pace on the retina of diabetic patient and conversely take appropriate measures.
Phacoemulsification is the modern method of cataract surgery, via this method lens substance is dissipated via ultrasound then aspirated and with minimal cut the lens is implanted. Apart from the forerunner surgical methods, phacoemulsification has some advantages: small incision, short rehabilitation period and high optical results.
Rational use of modern anti-cataract therapeutic and surgical measures provide effective treatment, giving high visual (optic) results for each individual patient.
MD, PhD, Ophthalmologist, Professor