LENS Lamia S Elewa Professor of Ophthalmology AinShams University Classification of Cataract -Chronological ∗ Congenital Cataract ∗ Acquired Cataract 1-Senile cataract (age related) 2- Complicated-Diabetic -Traumatic - Drug induced Classification of Cataract Anatomical/Morphological ∗ Sub-capsular - Ant - Post ∗ Cortical ∗ Nuclear ∗ More than 30% presents with mixed opacities Subcapsular Cataract Ant. S.C PSC 1-Posterior Subcapsular (PSC) Risk factors Circular, granular opacities in the centre of the pupil just in front of the post capsule Age, smoking, diabetes, steroid use, trauma Refractive changes None /any symptoms/signs • Can be very visually debilitating, especially under glare, near VA worse than distance VA • occur in younger age groups. • Tints for disability glare (vision loss with glare) Yes O/E 2-Nuclear Cataract Nuclear Cataract Description Homogeneous increase in light scatter in lens nucleus. Blue wavelength absorption also leads to increased yellowing. Risk factors Age, smoking, low levels of anti-oxidant vitamins. Refractive changes Myopic shift symptoms/signs Color vision changes (blue-yellow confusion) Tints for blue disability glare (vision loss with glare) These patients already have a built-in blue disability absorbing tint .Christmas tree cataract crystals seen in nucleus • Brunescent cataracts are very advanced nuclear cataracts that have become brown and opaque. 3-Cortical Cataract Early Vacuoles Later Radial spokes Cortical Cataract o Wedge shaped opacities found in the ant/post lens cortex o The base of the wedge is in the periphery of the lens, hidden by the iris. o found in the inferionasal part of the lens, which may implicate UV involvement in ae. o Cortical opacities are associated with water clefts, which are optically clear wedges. o Vision is only affected if the cortical spokes enter the pupillary area. Cortical Cataract o The visibility of cortical cataracts at the slit-lamp results from gross backscatter (i.e. towards the observing clinician), however, forward scatter (i.e. towards the retina) also occurs and this is responsible for the decrease of vision. It is important to note that backscatter and forward scatter are not necessarily highly correlated, thus a cortical spoke which is highly visible at the slit-lamp may not necessarily be causing a decrease in the patient’s vision. o Cause light scattering with variation in RI and pt complains of astigmatic changes & monocular diplopia Cortical cataract Description Risk factors Wedge-shaped opacity in the lens cortex with the base in the lens periphery, Age, ultra-violet light, female gender Refractive changes symptoms/signs Possible astigmatic changes. Monocular diplopia, sometimes asymptomatic despite obvious cataract on slit-lamp examination. Tints for disability glare (vision loss with glare) No, patients with these cataracts see worse with a larger pupil Cortical Cataract spoke-like (wheel) peripheral changes are seen. These changes may be extensive but may not affect Snellen visual acuity since they occur in the periphery. ∗ quoted from CONGDON et al Advanced cortical cataract ∗ Although this type of cataract may be compatible with a Snellen visual acuity of 20/40 or better, it may give rise to severe glare disability Classification according to maturity ∗[ ∗ ‘ Comment on Lens Clinically! Classification schemes: Conventional ∗ Lens Opacities Classification System (LOCS) III ∗ Oxford Clinical Cataract Classification and Grading System LOCS III LOCS III grades cataract in four dimensions: ∗ nuclear colour (NC) ∗ nuclear opalescence (NO) ∗ cortical opacity (C) ∗ PSC (P) ∗ Nuclear opalescence and colour are rated on a decimal scale from 0 to 7 ∗ cortical and PSC are rated on a decimal scale from 0 to 6. This is a thoroughly validated system which has been used extensively for clinical trial The conventional 0 to 4 grading system ∗ 0 is a clear lens, ∗ ∗ ∗ ∗ ∗ . Alternatively, PSC and cortical cataract can be + or 1+ represents a mild cataract, graded by the ++ or 2+ a moderate cataract, percentage of the +++ or 3+ a marked cataract (dilated or otherwise) and ++++ or 4+ a severe pupillary area they cataract occupy or by a brief sketch Cataract associated with Ocular disease ∗ ∗ ∗ ∗ PSC in myopia PSC in Retinitis Pimmentosa Uveitis acute increase in IOP causes focal necrosis of the subcapsular epithelium and localized, fleck-like opacities (glaukomflecken). Hesham Ghareib Q:Visual aberrations in patient presenting with Cataract ∗ Visual aberrations varies depending on the type of cataract. 1- Decreased visual acuity ∗ is the most common complaint. ∗ Mild degree of PSC cataract produces severe reduction in VA with near acuity affected > distance vision ∗ Nuclear sclerotic cataracts often are associated with decreased distance acuity and good near vision. ∗ A cortical cataract generally is not clinically relevant until late in its progression when cortical spokes compromise the visual axis. However, instances exist when a solitary cortical spoke occasionally results in significant involvement of the visual axis. Q:Visual aberrations in patient presenting with Cataract (continued) 2- Glare ∗ Glare may include an entire spectrum from a decrease in contrast sensitivity in brightly lit environments or disabling glare during the day to glare with oncoming headlights at night. ∗ Glare is prominent with PSC cataracts and, to a lesser degree, with cortical cataracts or nuclear. ∗ Many patients may tolerate moderate levels of glare without much difficulty, and, as such, glare by itself does not require surgical management. Q:Visual aberrations in patient presenting with Cataract (continued) 3-Myopic shift ∗ The progression of nuclear cataracts increases the diopteric power of the lens resulting in a mild degree of myopia or myopic shift. ∗ Consequently, presbyopic patients report less need for reading glasses as they experience the so-called second sight. As the optical quality of the lens deteriorates, the second sight is eventually lost. ∗ Typically, myopic shift and second sight are not seen in cortical or PSC cataracts. ∗ Furthermore, asymmetric development of the lensinduced myopia may result in significant symptomatic anisometropia that may require surgical management. Q:Visual aberrations in patient presenting with Cataract (continued) 4-Monocular diplopia ∗ sometimes, the nuclear changes are concentrated in the inner layers of the lens, resulting in a refractile area in the center of the lens. ∗ Monocular diplopia is not corrected with spectacles, prisms, or contact lenses. Q. Risk Factors for Cataracts in Diabetes ∗ Diabetics are 2-5 times more likely to develop cataracts than their non diabetic counterparts. ∗ The risk increases in diabetics< 40yrs of age ∗ Even Impaired fasting glucose (IFG) has been considered as a risk factor for cortical cataracts. ∗ B.m of the lens / lens capsule is thicker in diabetics. ∗ Type II D.M correlates with cortical opacities. ∗ Progresses rapidly ∗ PSC lens opacities in newly diagnosed diabetics. ∗ Snow-flake cataract or true diabetic cataract is typically seen in young diabetics with uncontrolled FBS Snow-flake Cataract Q. Anterior segment changes in Diabetics ∗ Cornea: Diabetic keratopathy; detectable changes as increased epithelial fragility, recurrent erosions, reduced corneal sensitivity, impaired wd healing, altered endothelial barrier function, corneal edema and infectitous ulcers ∗ Lens: cataract formation;thick B.M (lens capsule, cortical lens opacities, PSC , (any significant association with nuclear?), True diabetic cataract in younges. ∗ Iris: Miotic pupil, pigment dispersion (hypoxia),NVI---neovascular glaucoma. ∗ Glaucoma: Ocular hypertension, POAG. Neovascular glaucoma (detailed) --- Ocular ischemia ∗ Refractive Changes: hyperglycemia is the major cause of transient refractive changes in diabetics. Morphlogical and functional changes in the lens. Q. Iatrogenic cataract Drug Induced 1- Steroids Topical Std Systemic Std Intravitreal Std 2-Miotics 3-phenothiazine antipsychotics and the anti-cancer drug busulfan. After Vitrectomy -higher oxygen levels near the crystalline lens induce a nuclear cataract. With vitreous syneresis, or after vitreous removal, the lens has much greater exposure to oxygen levels from the choroid, and this induces nuclear sclerosis.
