Investigations required for cataract evaluation
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This document provides guidance on evaluating patients for cataract surgery. It outlines the important pre-operative steps including: obtaining a medical and ocular history, assessing vision, performing an eye exam to evaluate the lens and other structures, checking tear duct patency, measuring intraocular pressure and eye dimensions, and determining the appropriate intraocular lens power. Key tests and considerations are discussed to optimize surgical outcomes and identify any risks or limitations.
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Investigations required for cataract evaluation
- 2. CATARACT ■ Latin-waterfall ■ Any opacity in the lens or its capsule is called cataract ■ Cataract is the leading cause of vision loss. ■ Most common surgery performed on an outpatient basis.
- 3. INDICATIONS ■ Refractive ■ Medical ■ Therapeutic ■ Cosmetic
- 4. PRE OP CHECK LIST
- 5. HISTORY MEDICAL SURGICAL ALLERGY OCULAR . H/o of all systemicdiseases,curr entmedications patient is on Medications relevant to eye surgery(alpha blockers-floppy irissyndrome,Steriods- delayedhealing&a mp;amp;IoP, Antihypertensive- e;lectrolyteimbalance Metabolic cataracts . Previous surgeries Past ocular surgeries(glaucoma/ Cataract ) . Drug allergy to sulfonamides ,localanaestheticsand other antibiotics Ocular Symptoms Like Blurring OfVision,colouredHalos,diplopia,glare Duration And Progression H/O Of Previous Intraocular Disease H/O Previous Cataract Surgery H/O Intraocular Injuries
- 6. OTHER HISTORY ■ Factors limiting patients ability to cooperate or lie comfortably on the operating room table:- ■ Deafness ■ Language barrier ■ Dementia ■ Claustrophobia ■ Restless leg syndrome ■ Head tremor ■ Musculoskeletal disorder
- 7. VISUAL ACUITY ■ Visual acuity should be determined both for distance and for near. ■ . PSC :Greatly impaired near vision ■ Nuclear cataract : myopic shift (patient experience second sight) nuclear sclerosis, diminution of near vision more than that for distance should alert us to the possibility of macular dysfunction ■ Cortical cataract: Hyperopic shift
- 8. OCULAR EXAMINATION ■ Head posture ■ External eye posture: prominent eye brow, Enophthalmos : may affect surgical approach ■ LIDS: Entropion ,Ectropion ,Eyelid closure abnormality : adversely effect post operative recovery,Acne rosacea : risk of endophthalmitis and should be treated before cataract surgery ■ CONJUCTIVA:Inflammation ■ CORNEA: Assessment of corneal thickness is important ,Specular reflection – endothelial cell count and cell morphology ■ ANTERIOR CHAMBER-Shallow (intumescent of lens or forward displacement by posterior pathology) . Gonioscopy to rule out the angle abnormalities (synechia, neovascularization)
- 9. ■ PUPIL- Reacting promptly to light-both direct and consensual , Presence of RAPD-Implies substantial additional pathology , Readily dilating with mydriatics ■ LENS-Grading-planning size of incision & type of surgery . Nuclear cataract are harder and need more power with phaco . Black nuclear opacity-extremely dense-ECCE . Postr polar cataract-prevent posterior capsular dehiscence and subsequent vitreous disturbances- avoid HYDRODISSECTION
- 10. DUCT PATENCY ■ ROPLAS-Regurgitation on pressure over the lacrimal sac (ROPLAS) ■ Also,Tested by syringing ■ aim - to exclude chronic dacryocystitis, a major risk factor for postoperative endophthalmitis. ■ If either no block or both upper and lower canaliculi block taken for surgery
- 11. FUNDUS EXAMINATION ■ Retinal and optic nerve function must be assessed pre- op,Because if it is defective operation becomes valueless. ■ ARMD,RETINAL DETACHMENT Can adversely affect visual outcome ■ In eyes with very dense opacity,when fundus cannot be seen 5 tests are of value 1.PROJECTION OF LIGHT ■ 2 POINT LIGHT DISCRIMINATION ■ 3.MADDOX ROD ■ 4.ENTOPIC VIEW OF RETINA ■ 5.USG B SCAN-r/o vitreous haemorrage,retinal detachment,intraocular tumour & posterior staphyloma. Foveal ERG
- 12. INTRAOCULAR PRESSURE MEASUREMENT ■ Using Schiotz tonometry /non contact air puff tonometry ■ Can be raised due to swelling of lens in INCIPIENT STAGE/due to phacolytic glaucoma in which case extraction is indicated. ■ pre-existing Primary glaucoma ■ If glaucoma, medically controlled- lens extraction ■ If NOT,perform a trabeculectomy followed by cataract extracion/combined procedure.
- 13. A-SCAN BIOMETRY ■ To calculate lens power result in desired post operative refractive outcome ■ Two parameters: Keratometry Axial length ■ KERATOMETRY ■ Determines the curvature of anterior corneal surface ■ K1&K2 Readings obtained ■ For planning incision site along steepest meridian ■ To calculate IOL power
- 14. AXIAL LENGTH MEASUREMENT ■ A scan ultrasonography: Direct contact Immersion method Optical coherence biometry: Utilize two coaxial partially coherent low energy laser beam 22-25 mm and mean refractive power -25.0 -+1.0 D.
- 16. IOL POWER CALCULATION ■ Use SRK formula (Sanders, Retlaff & Kraff) P = A – 2.5L – 0.9K P ■ Lens implant power for emmetropia (D) L : Axial length (mm) K : Average keratometric reading (D) A : Constant specific to the lens implant to be used That A = 113 for AC lenses & 119 for PC lenses. many other formulas like HAIGIS,HOFFER,HOLLADAY etc are also used. ■ SRK2: If AL is < 20mm then A + 3.0 ■ If AL is 20 - 20.99 mm then A + 2.0 ■ If AL is 21 - 21.99mm then A + 1.0 ■ If AL is 22 - 24.0mm then A ■ If AL is > 24.5 then A - 0.50
- 17. B-SCAN ■ Two dimensional B-scan -tool for the detection of hidden posterior segment lesions.
- 18. BLOOD INVESTIGATIONS ■ NORMAL-RBS,CBC,RFT,S,ELECTROLYTES ■ SCREENING FOR VIRAL MARKERS ■ APTT,PT INR-in patients with individual risk factors or planned for general aneasthesia, ■ OTHER INVESTIGATIONS ■ ECG ■ CXR
- 19. THANK YOU