2DefinitionA cataract is an opacity in the natural lens that can cause visual problems.
3Why is it important?Age-related cataract is responsible for 48% of world blindness, which represents about 18 million people, according to the World Health Organization (WHO).At least 5-10 million new visually disabling cataracts occur yearly, with modern surgical techniques resulting in 100, ,000 irreversibly blind eyes.
41.2% of the entire population of Africa is blind, with cataract causing 36% of this blindness. In a survey conducted in 3 districts in the Punjab plains, the overall rates of occurrence of senile cataract was 15.3% among 1269 persons examined who were aged 30 years and older and 4.3% for all ages. This increased markedly to 67% for ages 70 years and older.
5In the UK 30% of persons of 65 years and over have visually impairing cataract in one or both eyes. It is estimated that 2.4 million people aged 65 and older in England and Wales have visually impairing cataract in one or both eyes
6An analysis of blind registration forms in the west of Scotland showed senile cataract as one of the 4 leading causes of blindness.
7AnatomyThe lens is surrounded by a thick lens capsule which is the basement membrane of the lens epithelial cells.Epithelial cells at the lens equator continue to be produced throughout lifeOlder lens fibres are compressed into a central nucleusYounger fibres around the nucleus make up the cortex.
23Congenital cataract Present at birth or appear shortly thereafter These cataracts may show many different patterns.The opacity may be confined to the area of the embryonic or fetal nucleus with clear cortex surrounding this.
29Assessment Vision acuity test Slit lamp Ophthalmoscopy In most cases, eye drops are used to dilate pupils before the exam.Tonometry
30TreatmentIf symptoms from a cataract are mild, a change of glasses may be all that is needed for you to function more comfortably.Surgery is the only way to remove the cataract.Cataract surgery should be considered when cataracts cause enough loss of vision to interfere with daily activities.
31Types of cataract surgery IntracapsularExtracapsularPhacoemulsificationECCE
32Extracapsular cataract extraction is the preferred method of cataract surgery It preserves the posterior portion of the lens capsulePosterior chamber IOL can be implanted in the capsular sacAn IOL is a tiny, transparent, convex lens made of different materials which is inserted in the eye during surgery.
34GlaucomaA group of disorders in which there is eventual development of an optic neuropathy with characteristic changes at the optic nerve head.Depression of visual function and eventual loss of visual field.Raised intra-ocular pressure often appears to be a significant factor in its development.
35Why is glaucoma important Glaucoma causes significant visual disability in the UK, accounting for 15% of registrable blindnessIn a white population, POAG occurs in approximately 1-2% of the population over 40, increasing with age to 4% or more of the over 80-year olds.
36Anatomy and physiology Schwalbe lineTrabeculumSchlemm canalScleral spurIris processes
37Aqueous is actively secreted by the non-pigmented epithelium of the pars plicata (anterior) of the ciliary bodyApproximately 90% of aqueous leaves through the trabeculum into the Schlemm canal and drains into episcleral veins (trabecular or conventional route)
3810% of aqueous passes across the face of the ciliary body into suprachoroidal space and then drains into the venous system (uveoscleral or unconventional route)
39IOP can be reduced by Reducing the aqueous production Increasing the aqueous outflow
40Optic nerve head 2% of population have cup-disc ratio > 0.7 Small physiological cupLarge physiological cupNormal vertical cup-disc ratio is 0.3 or less2% of population have cup-disc ratio > 0.7Total glaucomatous cupping
41Classification Primary congenital forms Primary open-angle glaucomas (POAG)Primary juvenile glaucomaPOAG/high pressure glaucomaPOAG/normal pressure glaucomaPrimary open-angle suspectOcular hypertensionEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.
43Primary open-angle glaucomas (POAG) Glaucomatous optic atrophyNormal pressure glaucomaOnline Journal of OphthalmologyPrimary open-angle glaucoma (POAG) is one of the leading causes of visual impairment and blindness in the UK.1POAG can encompass a range of disorders, which can be characterised as generally bilateral, but often asymmetric, progressive optic neuropathies and an open anterior chamber angle.2,3POAG may be categorised as normal pressure when IOP is normal without treatment, although other typical characteristics exist.1ReferencesKroese M, Burton H. J Epidemiol Community Health 2003;57:752–754.European Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.American Academy of Ophthalmology. Preferred Practice Pattern – Primary Open-Angle Glaucoma, 2005.43
44Primary angle-closure Acute angle-closureAcute/intermediate angle-closureOnline Journal of OphthalmologyPrimary angle-closure glaucoma is defined by the presence of iridotrabecular contact and a number of mechanisms may be responsible for appositional or synechial closure of the anterior chamber.1Three forms of the condition may manifest2,3:Acute, symptomatic form, uncommon in Europe, which may or may not lead to significant glaucomatous optic nerve damageIntermediate mildly symptomatic formChronic, asymptomatic formPrimary angle-closure can be staged into the following three groups1,2:Primary angle-closure suspectPrimary angle-closurePrimary angle-closure glaucomaReferencesEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Foster PJ et al. Br J Ophthalmol 2002;86:238–242.44
45Lens-induced secondary open-angle glaucoma Glaucoma classification Secondary open-angle glaucomas caused by ocular diseaseExfoliative glaucomaPigmentary glaucomaLens-induced secondary open-angle glaucomaGlaucoma associated with intraocular haemorrhageUveitis glaucomaGlaucoma due to intraocular tumoursGlaucoma associated with retinal detachmentOpen-angle glaucoma due to ocular traumaEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.45
46Secondary open-angle glaucomas Heterochromic iridocyclitis fuchs (uveitis), secondary open-angle glaucomaPigment dispersion syndromeUveitis glaucomaThis classification may be given when uveitis is associated with elevated IOP, optic nerve and/or visual field defects.1Pigment dispersion syndromeThis condition is typically characterised by dense trabecular pigmentation4 caused by the accumulation of melanin granules in the trabecular meshwork, resulting in open anterior angle chambers.2,3Exfoliative glaucomaThis condition occurs as a result of exfoliative syndrome, an age-related disorder of the extracellular matrix. It predisposes to both open-angle and angle-closure glaucoma.4ReferencesMoorthy RS et al. Surv Ophthalmol 1997;41:361–394.European Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Ritch R. Am J Ophthalmol 1998;126:442–445.Ritch R. Curr Opin Ophthalmol 2001;12:124–130.Exfoliative glaucomaOnline Journal of Ophthalmology:46
47Lens-induced (phacolytic) glaucoma Phacomorphic malignant glaucomaLens-induced secondary open-angle glaucoma is caused when lens protein obstructs the trabecular meshwork.1Lens proteins may be associated with a cataract, cataract surgery, or other trauma/surgery to the lens.1Phacolytic glaucoma is the term given specifically to obstruction by lens protein from a mature or hypermature cataract with intact capsule.1ReferenceEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Phacolytic glaucoma, histologyPhacolytic acute open-angle glaucomaOnline Journal of Ophthalmology:47
48Secondary open-angle glaucomas Neovascular secondary glaucoma Neovascular secondary angle-closure glaucomaNeovascular glaucoma is an uncommon type of glaucoma that is difficult to treat and often results in blindness.1The condition is most commonly caused by diabetic retinopathy, ischaemic central retinal vein occlusion and ocular ischaemic syndrome.1Other uncommon causes include ocular radiation, ocular tumours, uveitis and other retinal diseases.1Ischaemia of the optic nerve head and/or retina is the main reason for visual loss with high IOP.1ReferenceHayreh SS. Prog Retin Eye Res 2007;26:470–485.Florid iris neovascularisationOnline Journal of Ophthalmology:48
49Secondary open-angle glaucomas Trauma and secondary glaucoma Lens luxation with acute pupillary block glaucomaSeveral mechanisms can lead to glaucoma following ocular trauma.1Secondary traumatic glaucomas can be caused by both open-angle and angle-closure pathomechanisms.1Examination may reveal the following:Chemical burnsHyphemaTraumatic cataractSwollen lensUveitisAngle recessionRuptured iris sphincterReferenceEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Hyphema, total, secondary open-angle glaucomaOnline Journal of Ophthalmology:49
50Risk factors for angle-closure Shallow anterior chamber depth, associated with1:Female genderIncreasing ageAsian (particularly Chinese) originShorter globe axial length1Environmental factors1:Seasonal variationExtreme temperaturesProlonged periods indoors in a dark environmentAn association has been found between a shorter axial length and a higher incidence of primary angle-closure.1The demographic risk factors of female gender, Asian origin and elderly age all contribute to a shallow anterior chamber, which is associated with the highest risk of angle-closure glaucoma.1ReferenceFoster PJ. Semin Ophthalmol 2002;17:50–58.1. Foster PJ. Semin Ophthalmol 2002;17:50–58.50
51Patient history POAG is often asymptomatic Angle-closure glaucoma Eye pain and rednessHalosHeadachesThe first step in the diagnosis of glaucoma is assessment of presenting complaint. Most glaucomas are asymptomatic until well advanced, therefore identification may have to be reliant on assessment of risk factors and assessment of glaucomatous changes.Glaucoma symptoms that may be noted are visual blurring and discomfort, haloes around lights and/or glare, poor light to dark adaptation, and difficulty in tracking fast-moving objects.1Taking a comprehensive medication history is also essential as there are certain medications that may lead to glaucoma or glaucoma-like conditions. These include:Steroids – associated with ocular hypertension and open-angle glaucomaAnticholinergics/tricyclic antidepressants – associated with angle-closure glaucomaAnticonvulsants – associated with nasal peripheral loss without disc changesFamily history must also be noted due the hereditary nature of primary open-angle glaucoma.2ReferencesSouth East Asia Glaucoma Interest Group (SEAGIG). Asia Pacific Glaucoma Guidelines, 2003.Tielsch JM et al. Arch Ophthalmol 1994;112:69–73.South East Asia Glaucoma Interest Group (SEAGIG). Asia Pacific Glaucoma Guidelines, 2003.51
52Ophthalmic historyTrauma, previous eye surgery or laser, previous ophthalmic medicationsMedication historySocial historyFamily historyRisk factors in familyBlindness or eye disease in the family
53Examinations & investigations Visual acuitySlit-lamp examinationApplanation tonometryGonioscopyOptic nerve head and retinal nerve fibre layer evaluationVisual field examination (perimetry)PachymetryAll patients should undergo a comprehensive physical eye examination.An ophthalmologist should ensure that they have the necessary equipment and training to provide1:Complete examination of the pupil, anterior segment, optic nerve head and retinal nerve fibre layer, and fundusMeasurement of IOP, central corneal thickness, visual field and visual acuityReferenceAmerican Academy of Ophthalmology. Preferred Practice Pattern – Primary Open-Angle Glaucoma, 2005.53
54Examinations & investigations Slit-lamp examination Online Journal of OphthalmologyDuring the glaucoma assessment, slit-lamp examination should be used to assess:The pupils for reactivity and an afferent pupillary defect1The anterior segment, prior to and after dilation, for evidence of physical findings associated with narrow angles, corneal pathology, or a secondary mechanism for elevated IOP such as pseudoexfoliation, pigment dispersion, iris and angle neovascularisation, or inflammation1,2The fundus, through a dilated pupil whenever feasible, in order to search for other abnormalities that might account for visual field defects (e.g. optic nerve pallor, tilted disc, disc drusen, optic nerve pits, optic nerve hypoplasia, neurological disease, macular degeneration, and other retinal disease)1Optimal examination of the peripheral retina requires the use of the indirect ophthalmoscope or slit-lamp fundus biomicroscopy. Optimal examination of the macula and optic nerve requires the use of the slit-lamp biomicroscope and accessory diagnostic lenses1Slit-lamp biomicroscopic examination should also include the eyelid margins and lashes, tear film, conjunctiva, sclera, cornea, anterior chamber, and assessment of peripheral anterior chamber depth, iris, lens, and anterior vitreous.2ReferencesAmerican Academy of Ophthalmology. Preferred Practice Pattern – Primary Open-Angle Glaucoma, 2005.American Academy of Ophthalmology. Preferred Practice Pattern – Comprehensive Adult Medical Eye Evaluation, 2005.Acute angle-closure glaucoma54
55Examinations & investigations Slit-lamp examination – applanation tonometry National Eye Institute, National Institutes of HealthThe Goldmann applanation tonometry (GAT) mounted at the slit lamp is the gold standard for assessment of IOP.1Before use, it is important to ensure that the tonometer is calibrated to the desired threshold tension levels.2Topical anaesthesia must be applied as the prism tip must touch the cornea.If GAT is unavailable or unsuitable for the patient, other tonometry methods that may be employed are1:Air puff tonometryPneumatonometryTono-Pen XLOcuton self-tonometryPascal dynamic contour tonometry (DCT)Ocular Response Analyser (ORA)Rebound (Icare) tonometryReferencesEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.South East Asia Glaucoma Interest Group (SEAGIG). Asia Pacific Glaucoma Guidelines, 2003.European Glaucoma Society, 200855
56Examinations & investigations Direct gonioscopy European Glaucoma Society, 2008Direct gonioscopy allows the use of contact goniolens to permit the light from the anterior chamber to pass through the cornea so that the angle may be viewed.1The most commonly used lenses for direct gonioscopy are:Koeppe (contact fluid required)Layden (sized for infants; contact fluid required)WorstFor this procedure, the patient must be lain on their back. A direct view of the anterior chamber angle is possible and both eyes can be compared simultaneously.1ReferenceEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Rich R, courtesy of South East Asia Glaucoma Interest Group (SEAGIG).56
57Assessment of the optic disc Observe the scleral ring to size the optic discIdentify the size of the rimExamine the RNFLOptic nerve head (ONH) and retinal nerve fibre layer (RNFL) evaluation can be divided into two parts1:QualitativeContour of the neuroretinal rimOptic disc haemorrhagesPeripapillary atrophyBared circumlinear vesselsAppearance of the RNFLQuantitativeOptic disc size (vertical disc diameter)Cup/disc ratio (vertical)Rim/disc ratioRNFL heightCareful study of the optic disc neural rim for small haemorrhages is important as these may precede visual field loss and further optic nerve damage.2ReferencesEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Drance S et al. Am J Ophthalmol 2001;131:699–708.Examine the region of the peripapillary atrophyLook for retinal and optic haemorrhagesPhotographs by Ki Ho Park, courtesy of South East Asia Glaucoma Interest Group (SEAGIG).57
58Optical coherence tonometry Examinations & investigations Optic nerve head/retinal nerve fibre layer imagingRed-free photographyOptical coherence tonometryThe preferred technique for optic nerve head and retinal nerve fibre layer evaluation involves magnified stereoscopic visualisation, preferably through a dilated pupil. Red-free illumination may aid in evaluating the retinal nerve fibre layer.1Colour stereophotography or computer-based image analysis of the optic nerve head and retinal nerve fibre layer are the best currently available methods to document optic disc morphology and should be performed.1Newer imaging techniques are now available for documentation of the optic disc. These include2,3:The Heidelberg retinal tomogram (HRT)Scanning laser polarimetry (GDx)Optical coherence tomography (OCT)Retinal nerve fibre layer imaging by OCT is reliable, despite the fact that age, ethnicity, axial length and optic disc size can affect the machine’s normative range. Also, scan quality can be affected by movement, media opacities, myopia and severity of disease.4The HRT is considered a promising tool, although the relationship between progressive structural and visual field change has yet to be fully elucidated.5ReferencesAmerican Academy of Ophthalmology. Preferred Practice Pattern – Primary Open-Angle Glaucoma, 2005.European Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Thomas R, Parikh RS. Community Eye Health 2006;19:36–37.Chang R, Budenz DL. Curr Opin Ophthalmol 2008;19:127–135.Strouthidis NG, Garway-Heath DF. Curr Opin Ophthalmol 2008;19:141–148.Ki Ho Park, courtesy of South East Asia Glaucoma Interest Group (SEAGIG).58
59Examinations & investigations Visual field examination – perimetry Testing of visual field is mandatory in glaucoma assessment and management1 in order to define the state of optic nerve function and visual impairment.All patients with glaucoma or suspected glaucoma should undergo frequent visual field examinations.2Standard automated perimetry (SAP) is the preferred technique for evaluating the visual field.1,3Kinetic testing is an acceptable alternative when patients cannot perform SAP or if it is not available.3 However, the method is not considered suitable for detection of early glaucomatous field loss and small defects may be lost between isopters.1It is important to use a consistent examination strategy when visual field testing is repeated.3Characteristics of glaucomatous visual field defects include4:Asymmetrical across horizontal midline in early/moderate casesLocated in mid-periphery, 5–25 degrees from fixation, in early/moderate casesReproducibleNot attributable to other pathologyClustered in neighbouring test points (localised)Defect should correlate with the appearance of the optic disc and neighbourhood.ReferencesEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Chauhan BC et al. Br J Ophthalmol 2008;92:569–573.American Academy of Ophthalmology. Preferred Practice Pattern – Primary Open-Angle Glaucoma, 2005.South East Asia Glaucoma Interest Group (SEAGIG). Asia Pacific Glaucoma Guidelines, 2003.Mild loss of visual fieldSevere loss of visual field59
60Treating the mechanisms of glaucoma1,2 Medical RxIOP reductionLaser trabeculoplastyAbnormal anatomyWork with multidisciplinary team to treat systemic problemsContributing diseasesLaser iridoplasty IridotomyLens extraction Vitreous surgeryReduction of IOPChoose the appropriate medication1,2:Most likely to reach target IOPBest safety profileMinimal inconvenienceStart with monotherapy wherever possible.1,2Laser trabeculoplasty is also an effective treatment option.2Treatment of angle-closureTreatment may involve1:Deepening of peripheral angle-closureIridotomy – to reduce pupil blockArgon laser peripheral iridoplasty – to flatten peripheral irisLens extraction – to reduce pupil block and displace iris posteriorlyVitreous surgeryReferencesSouth East Asia Glaucoma Interest Group (SEAGIG). Asia Pacific Glaucoma Guidelines, 2003.European Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.Filtration surgery trabeculotomy1. South East Asia Glaucoma Interest Group (SEAGIG). Asia Pacific Glaucoma Guidelines, 2003.2. European Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.60
61Glaucoma treatment Pharmacological medication Laser treatment Surgery Objective: to review the different options for treatment of underlying disease mechanisms and abnormal eye anatomyPharmacological medicationLaser treatmentSurgery6161
65Laser treatment Angle closure and angle-closure glaucoma Laser iridotomy – pupillary block reliefLaser iridoplasty (gonioplasty) – modification of iris contourCyclophotocoagulation – inflow reduction for end-stage glaucoma65
66Surgery Incisional surgery options for glaucoma Characteristics requiredType of surgeryOpen-angle glaucomaOutflow enhancementGlaucoma drainingFiltering surgery*Drainage deviceChronic angle-closure glaucomaPupillary block reliefWidening of anterior chamber angle inletIridectomyTrabeculectomyLens extractionAcute angle closure (± glaucoma)Angle surgeryGoniosynechialysisChildhood glaucomaAngle SurgeryGlaucoma drainageGoniotomy/trabeculotomyTrabeculectomy†There are various incisional surgery techniques, whose indications depend on the type of glaucoma being treated. The decision to use a particular type of surgery should depend on1:The target IOP for that individual patientPrevious ophthalmic historyRisk profileThe preferences and experiences of the surgeonThe patient’s opinions and expectationsPre-operative assessment should identify any risk factors for failure of surgery, which include2:Asian or African ethnicityPrevious surgeryYoung ageAphakiaPseudophakiaActive ocular inflammationProlonged use of topical glaucoma medicationsTendency to form keloidsNeovascular glaucomaReferencesEuropean Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd ed), 2008.South East Asia Glaucoma Interest Group (SEAGIG). Asia Pacific Glaucoma Guidelines, 2003.66