Current Therapy in Ocular Disease -The Vision Institute of Canada-

Transcription

1 Current Therapy in Ocular Disease -The Vision Institute of Canada- Separating the Good, the Bad and the Ugly: Is It Glaucoma or Not Reducing the Pressure on Glaucoma Decision-Making Update and Clinical Perspectives on the Medical Management of the Glaucomas

2 Glaucoma Update References Epidemiology / Definition Risk Factors Clinical Evaluation Visual Fields / Scanning Technology Treatment Goals Medications Cases

3 Keep Current with the Literature However, many current practitioners of ophthalmology are still way behind the times, depending on what old so-and-so taught me rather than keeping up with current thinking and controversies. Donald S. Minckler, MD, Ophthalmology Times, January 15, 2004 Sadly, this is undoubtedly true for optometry as well ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Glaucoma Today FREE Website: Telephone:

4 Excerpts From: The International Glaucoma Review, World Glaucoma Congress The International Glaucoma Review: The Journal of the World Glaucoma Association ( is published every four months. This expert publication reviews the world glaucoma literature from the previous four months and provides abstracts and reviews of the most salient information from that time period in a single publication. We are pleased to provide for you, our colleagues in optometry, selected quotes (or in-context paraphrases), and our commentaries. Randall K. Thomas, OD & Ron Melton, OD

5 Internet Resources - Glaucoma A Broad Stroke (Glaucoma Research Foundation) Intermediate Complexity Detailed Information Economic Assistance Surgery Chats (Glaucoma Group) Reference: Internet Resources by Nathan M. Radcliffe, MD, Glaucoma Today, Summer 2010

6 Glaucoma Epidemiology Second only to cataracts as the leading cause of blindness in world 67 million people in world have glaucoma (10% blind) 3 million in U.S. have disease (half undiagnosed) Average age of onset 54 years of age Estimated 120,000 Americans blind from glaucoma Leading cause of irreversible blindness among patients of African descent million glaucoma suspects Over 8 million office visits per year

7 Glaucoma is common, on the rise, underdiagnosed, costly, distressing to those affected and their families, and disabling. As the population increases, so does the absolute number of glaucoma sufferers. In addition, with glaucoma prevalence increasing exponentially with age, glaucoma numbers are rising with the rapidly aging population. Glaucoma patients are estimated to rise in number from 60 million in 2010 to nearly 80 million in 2020, with more than half in developed societies remaining undiagnosed. In developing communities, the proportion undiagnosed is significantly higher. Varma R et al. An Assessment of the Health and Economic Burdens of Glaucoma. AJO. October 2011.

8 U.S. Life Expectancy / Death Rates U.S. life expectancy 77.9 (1.4 years increase last decade) Males (75.3) Females (80.4) For first time life expectancy black males reached 70 years Heart disease and cancer leading cause of death Estimated 11,061 deaths from HIV/AIDS in 2007 (mortality rate declined 10% from previous year) Infant mortality rate was 6.77 infant deaths per 1,000 live births. Information provided by Centers For Disease Control and Prevention s National Center for Health Statistics (

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10 Glaucoma Medications and Mortality After adjustment for potential confounding variables, the use of glaucoma medications was associated with a reduced likelihood of death in this large sample of US adults with glaucoma. Reference: Joshua Stein, MD et al. Association Between the Use of Glaucoma Medications and Mortality. Archives of Ophthalmology. February 2010

11 Longevity and Glaucoma Care The typical patient with glaucoma who is white lives with the disease for an average of 12.8 years and one who is black lives an average of 16.3 years. Reference: Quigley. AJO. September Pp 458

12 Definition of Primary Open Angle Glaucoma POAG is a multifactorial optic neuropathy in which there is a characteristic acquired loss of optic nerve fibers. Evidence of typical visual field loss Note there is no mention of IOP!!! From the AAO s Preferred Practice Pattern regarding Primary Open-Angle Glaucoma

13 Primary Open Angle Glaucoma Suspect Large or asymmetric C/D ratios IOP greater than 21 mmhg after allowance for CCT

14 Normal-Tension Glaucoma (NTG) Defined as progressive optic disc damage and visual field loss due to glaucoma without evidence of elevated IOP. Etiology: mechanical and vascular factors may play role. Diagnosing NTG remains a process of exclusion Neuro work-up if: Neuro symptoms including cranial neuropathies, VF defects respect midline, rim pallor, APD, central VF loss, color vision loss Work-up Careful diurnal pressure Look carefully for optic disc hemorrhages More common in females and migraines Baseline photos, VF s, NFL Treatment: Meds, laser or trab

15 Underdiagnosis of POAG Population studies suggest over half of all glaucoma patients have not been diagnosed From the Baltimore Eye Study: One-half of all people who were found to have glaucoma had seen an eye doctor within the past year and were unaware they had glaucoma! Many suffer severe visual field loss before diagnosis.

16 Causes of Optometric Medicolegal Misadventures

17 Risk Factors For POAG Positive family history (age at Dx?) Suspicious ONH cupping Elevated or increasing IOP Subnormal central corneal thickness (CCT) Low diastolic blood pressure Advancing age (particularly after 50) African or Hispanic origin - onset earlier (about 10 years), damage more severe, treatment less successful Diurnal fluctuation? High myopia

18 Risk Factors for Development of Glaucoma Ocular Factors IOP CCT ON structure (C/D ratio) Disc hemorrhage Other ocular disorders Non-ocular Factors Age Race Family history/genetic predisposition Vascular disease (HTN, vasospasm)

19 Statins and Glaucoma: Protective? Statins may have an effect on the development of glaucoma independent of their cholesterol- lowering properties. Statin use was associated with VF stabilization over 3 years among patients with LTG. Might enhance aqueous outflow facility treating hyperlipidemia with a statin plays a protective role in patients with OAG, especially in the early stages of the disease. Our study shows a dose-response effect of statin exposure whereby the longer an enrollee was prescribed these medications, the greater the protective effect. Reference: Ophthalmology, October 2012

20 Risk Factors for Progression Peak IOP Thinner central corneal thickness A detected disc hemorrhage Presence of beta-zone parapapillary atrophy Peak IOP is a better predictor of progression than is IOP mean or fluctuation Reference: Archives of Oph. May 2011

21 Myopia: Risk For Developing Glaucoma Eyes with an increased axial length seem to have a greater deformability of the lamina cribrosa. On average, significant myopia confers a two-fold risk for the development of POAG Reference: Oph. October 2011.

22 Mean ocular perfusion pressure (MOPP) may be an additional modifiable risk factor that deserves additional research and clinical attention. Lower MOPP during F/U was associated with VF progression. An imbalance between IOP mechanical stress and blood supply leads to hypoxia, which may be responsible, at least partially, for axonal damage and retinal ganglion cell death. Even thought the calculation of estimated MOPP is subject to criticism, it appears to be a relatively robust estimator of the effects of low systemic blood pressure on the optic nerve. Reference: AJO. October 2012

23 Retinal Vein Occlusion and OHT There are no scientific studies to support decreasing IOP to prevent retinal vein occlusions. Reference: The Incidence of Retinal Vein Occlusion in the Ocular Hypertension Treatment Study. Ophthalmology, March 2010

24 Chase the Family First-degree relatives of identified OAG patients should be evaluated with optic disc and visual field testing. Among existing OAG patients, 1 in 8 has a living relative with undiagnosed glaucoma. We must be more aggressive in recommending examinations for family members of OAG patients. Screening in vans in the community may make us feel good but chasing family members is a more costeffective method to find some of the 50% of OAG patients who are presently undiagnosed. We must not only take a family history, but take the initiative in following up on family members. Harry A. Quigley, M.D. Archives of Ophthalmology, July 2006

25 Screening Relatives of Patients with Familial Chronic Open Angle Glaucoma Siblings of COAG patients had the highest risk of COAG developing (64.7%) compared with children (13.2%) or other blood relatives (22.2%). Conclusions: When COAG is present in more than one family member, immediate and other relatives should be evaluated for glaucoma by means of clinical examination and automated perimetry. Reference: R Nguyen et al. Ophthalmology 2000; 107

26 Is Diabetes a Risk Factor For Glaucoma? In this study (in the Netherlands), no association between diabetes and glaucoma was detected. This was in line with two other prospective studies. If there is any effect of diabetes, then it will be small, and protection is at least as likely as a negative influence. Reference: Ophthalmology, October, 2006

27 World Glaucoma Association on Fluctuation Insufficient evidence exists to support ideas that 24-hour IOP fluctuation or longer-term IOP variations (over periods of more than 24 hours) affect the risk of disease development or worsening. This information is important because the concept of IOP fluctuation as a risk factor has been popularized widely. Ophthalmology Times, Sept. 2007

28 IOP Fluctuation as a Risk Factor Controversy exists where there is no consensus Hypothesis: IOP fluctuation is damaging in patients with low IOP When the IOP is high, the mean IOP is the predominant risk factor Bottom line: When there is indecision regarding any potential risk factor, it cannot be of any major influence References: 1) Bengtsson, B, Heijl, A. Fluctuation of Intraocular Pressure and Glaucoma Progression in the Early Manifest Glaucoma Trial. Ophthalmology, Feb ) Caprioli, J. Intraocular Pressure Fuctuation. Archives of Ophthalmology, Aug. 2007

29 Impact of IOP on Visual Field Progression Regarding IOP risk: When IOP is high, mean IOP was key, but IOP variation was more predictive if IOP s were low. Not all POAG patients are the same: existing data suggest that the effects of IOP variation depend on the characteristics of the patient, the baseline IOP, their stage of damage, the type of glaucoma, and other as yet unknown factors. AJO, September 2011

30 Diastolic Blood Pressure Ocular Perfusion Pressure and Glaucoma OPP = diastolic BP IOP Theory: OPP <50mmHg is a risk factor for glaucoma, and glaucoma progression Examples: DBP of 65 and an IOP of 15 DBP of 85 and an IOP of 35 These two patients may be at equal risk because they have same theorized OPP of 50mmHg Take home message: Begin to check blood pressures on your glaucoma and glaucoma suspect patients, especially those with lower IOPs. Reference: In press

31 Under-Appreciation of Systemic Hypotension As It Relates To Ocular Perfusion OPP: IOP minus the diastolic blood pressure Ocular perfusion pressure: may be the single biggest risk factor for glaucoma onset and progression Reference: Liebmann JM. Optometric Glaucoma Society, Boston, October 2011.

32 Diastolic Blood Pressure Ocular Perfusion Pressure and Glaucoma The driving force for ocular blood flow is the ocular perfusion pressure (OPP), defined as the ocular artery pressure minus the IOP. Large cross-sectional prevalence studies in different populations found a significant association between low diastolic OPP and the prevalence of OAG. The greater incidence of progression in patients with lower blood pressure, seen mainly in patients with lower IOP, suggests a vascular risk factor for progression independent of IOP. Low blood pressure... may be the most important vascular risk factor for glaucoma progression. Reference: AJO. May 2010

33 OHTS Summary of Key Findings Topical treatment achieved 20% IOP reduction in patients with ocular hypertension The incidence of POAG was reduced >50% at 5 years 4.4 % in the medication group 9.5% in the observation group NOTE: 90% of untreated patients followed for 5 years did NOT convert to POAG.

34 OHTS Summary of Practice Implications Risk for progression of ocular hypertension to POAG can be assessed - Age, IOP, vertical C/D ratio, CCT CCT should be measured in all patients with ocular hypertension and all glaucoma suspects Patients at high risk should be treated Therapy should be selected based on efficacy, tolerability, and likelihood of patient compliance

35 Risk of POAG in Observation Group by CCT and Baseline IOP* The number of participants varies in each observation group. *Through Nov. 8, Gordon MO et al. Arch Ophthalmol. 2002;120:

36 Risk of POAG in Observation Group by CCT and Baseline Vertical C/D Ratio The number of participants varies in each observation group. *Through Nov. 8, Gordon MO et al. Arch Ophthalmol. 2002;120:

37 Correction values for applanation tonometer readings according to corneal thickness Calculation based on data of Ehlers et al (1975) Modified from Stodtmeister (1998) Arithmetic mean of corneal thickness in healthy subjects: 545 µm (Doughty and Zaman 2000) Correction values according to corneal thickness of 545 µm

38 Perspective on Pachymetry The World Glaucoma Association panel considered ways to measure IOP accurately. In particular, the measurement of central corneal thickness was identified as crucial. (Review of Ophthalmology, Aug. 2007) Almost 50% of OHTS participants had corrected IOP s below the recruitment threshold, suggesting that many of the participants may never have been at much risk of developing glaucoma. (Ophthalmology, Nov. 2007) CCT is the most heritable aspect of ocular structure (more than refraction, axial length, or optic disc size), suggesting that it is under exquisite genetic control. (Ophthalmology, Nov. 2007)

39 Perspective on Central Corneal Thickness (CCT) CCT has become standard-of-care in the POAG (or suspect) work-up Thinner corneas are a strong risk factor for POAG because true IOP is actually higher than the measured IOP. Some patients with measured ocular hypertension may simply have a thicker CCT, thus reducing POAG risk because the true IOP is actually less than the measured IOP

40 Role of CCT and Glaucoma Thinner CCT may be a significant, independent risk factor for open-angle glaucoma among persons with ocular hypertension. It is unclear whether the impact of CCT as a risk factor for glaucoma is mediated largely through its role in determining measured IOP, or whether the thickness of the cornea is a surrogate for greater susceptibility of the eye to damage. Reference: AJO, May, 2006

41 Corneal Thickness and Age Adult thickness is reached by age 10. While the cornea thins ever so slightly with age, repeating pachymetry is rarely indicated. It is important to know pre and post keratorefractive corneal thicknesses. Reference: AJO. November, 2004

42 Treatment of Ocular Hypertension In the end, the physician is stuck with the persistent problem of whom to treat and whom to watch. It probably still makes sense that young patients with lots of high risk factors should receive prophylaxis, while elderly patients with few risk factors should not. The endless symposia and debates on how to best manage patients with ocular hypertension will probably continue unabated. Reference: Sommer A. Editorial. Treatment of Ocular Hypertension. Archives of Ophthalmology. March, 2010.

43 Delaying Treatment of Ocular Hypertension In summary, the second phase of OHTS allows us to draw some important conclusions about the management of patients with OHT. Early medical treatment decreases the cumulative incidence of POAG. The absolute effect is greatest in high-risk individuals. Conversely, there is little absolute benefit of early treatment in individuals with OHT at low risk of developing POAG. Reference: Klass M et al. Delaying Treatment of Ocular Hypertension. Archives of Ophthalmology. March, 2010.

44 The general clinical evaluation of a new glaucoma suspect / patient This clinical evaluation builds upon a careful family history, personal medical history, current health status, and medication(s) Best corrected vision Document pupil size and reactivity Careful slit lamp biomicroscopy noting A/C depth, any iris abnormalities such as pigment dispersion, retroillumination defects, pseudo exfoliation, corneal guttata, etc. Applanation tonometry, noting time Pachymetry to determine CCT

45 Difficulty in Achieving Accurate Tonometry at The Slit Lamp Short stature, large stature, blepharospasm, large breasts, large bellies, cervical arthritis, being wheelchair-bound and other physical conditions can make slit-lamp-based IOP measurements challenging or impossible. Kowa or Perkins hand-held Goldmann applanation tonometers can largely override all these challenges. ICARE tonometry can also be an excellent surrogate also. Reference: AJO, April 2001; Ophthalmology, December 1998.

46 World Glaucoma Association on Tonometry From comparisons of different tonometers in the same population, it was concluded that there was insufficient evidence to recommend any method of measurement at the current time as being superior in Goldmann applanation tonometry. Reference: September 1, 2007, Ophthalmology Times

47 Perspective on Rebound Tonometry It may be considered a noncontact tonometer because the corneal touch is so quick that topical anesthesia is not necessary. It is good for children with whom contact tonometry can be difficult. In addition, some children are afraid of the air puff in noncontact tonometry. The ICARE rebound tonometry performs well even for inexperienced practitioners. It reads about 1.5 mm higher than Goldmann. Reference: Ophthalmology, January, 2008

48 Clinical Perspective on Rebound Tonometry The advantages of rebound tonometry include portability, lack of dependence on slit lamp mounting or even an external electrical source (battery powered), no need for topical anesthetic, ease of use, suitability for use by non-medically trained personnel, and toleration by young children and non-cooperative adults. These characteristics make it quite useful in screening situations. In my practice, this is our go to instrument for children as young as 3 years, for the intellectually challenged adults, and those with blepharospasm. Reference: R. Stamper, MD, Optometry and Vision Science. Jan. 2011

49 Comparison of Icare Rebound Tonometer With Noncontact Tonometer in Healthy Children IOP measurements performed using Icare are better tolerated in the pediatric population, as compared with measurements using NCT, especially in children below the age of 6 years. Reference: M Kageyama MD et al. Journal of Glaucoma. January 2011.

50 Glaucoma Work-Up (continued) Baseline gonioscopy (4-mirror preferred) looking for PAS, angle recession, angle pigmentation, and the anatomic patterns of the angle anatomy Thorough BIO to r/o any peripheral pathology Stereoscopic evaluation of the optic nerve heads (60D, 78D, or Hruby lens); glaucoma detected most often through dilated pupils Baseline static threshold visual fields Image analyzer of optic nerve head (GDX- VCC/OCT) Optic disc photographic documentation

51 Assessment of Patient Opinions of Different Clinical Tests Used in the Management of Glaucoma Goldmann applanation tonometry... was ranked significantly better than any other test. Short-wavelength automated perimetry was ranked significantly worse than any other test. Ophthalmology, December 2008

52 Breakthrough on Gonioscopic Training A most wonderful website exists to help teach superb gonioscopic anatomy and technique Please seek and study:

53 Agreement Among Glaucoma Specialists in Assessing Progressive Disc Changes From Photographs in Open- Angle Glaucoma Patients Conclusion: Interobserver agreement among glaucoma specialists in judging progressive optic disc change from stereophotographs was slight to fair. After masked adjudication, in 40% of the cases in which the optic disc appeared to have progressed in glaucoma severity, the photograph of the "worse optic disc was in fact taken at the start of the study. Caution must be exercised when using disc change on photographs as the gold standard for diagnosing open-angle glaucoma or determining its progression. Reference: H Jampel et al. AJO. January 2009 M&T Commentary: Perhaps serial Nerve Fiber Analysis is better for following preperimetric glaucoma, and serial visual fields are best for following established visual field defects.

54 Clinical Assessment of Stereoscopic Optic Disc Photographs for Glaucoma: The European Optic Disc Assessment Trial Conclusions: In general, ophthalmologists classify optic disc photographs moderately well for detecting glaucoma. There is, however, large variability in diagnostic accuracy among and agreement with clinicians. Common imaging devices outperform most clinicians in classifying optic discs. Reference: N Reus et al. Ophthalmology. April 2010.

55 Optic Nerve Head Evaluation Cup depth is critical - Stereopsis! Are cup walls steep or sloping? Note rim translucency and vertical elongation of the cup Is the cup concentric with the disc, or is the cup displaced? Is the neuroretinal rim thinned more at certain clock hours than others? Especially look for any accentuated erosion of the inferotemporal or superotemporal regions. Is the disc generally pink, yellowish, or pale?

56 ISN T Helpful diagnostic observation in ONH evaluation Normal neuroretinal rim anatomy follows the ISN T rule - Inferior rim should be thickest - Superior rim is slightly less thick - Nasal rim is slightly less thick - Temporal rim should be the thinnest Most ONH s are round or slightly vertically oval ISN T rule may not hold if ONH horizontally oval

57 Another Perspective on the ISNT Rule The findings from the current study contribute to the emerging clinical consensus that, as a single arbiter of open-angle glaucoma, the ISNT rule is of limited utility. Interesting: Discs with high IOP s tend to have more concentric cupping, whereas those with progressive damage at lower pressures tend to have more focal damage. Reference: Oph: April 2012

58 Optic Disc Size and Glaucoma Bergtson (25 yrs ago) Normal small discs have small cups Normal large discs have large cups. Disc Diameter Mean C/D Upper Limit Small mm Medium mm Large mm Average disc diameter 1.5mm Implications for glaucoma diagnosis and management A high ratio may not be pathologic C/D s for large discs change by a smaller amount C/D changes caused by glaucoma occur more slowly in large discs than in small discs (baseline photos large discs especially important C/D asymmetry is not always pathological

59 Sizing the Optic Nerve Head Jonas proposed that in routine practice, the clinician conduct a quick, crude estimate of whether the disk in question is average-sized (medium), smaller-than-average, or larger-thanaverage. Reference: AJO, September, 2006, pp

60 Tilted Optic Disks and Visual Field Defects Tilted disks often result in clinically measurable visual field loss Most common location: Superior temporal (33%) Second most common: Superior (25%) Defects can occur anywhere in the peripheral field, or even paracentrally Defects in tilted disks do not respect the vertical or horizontal midline Reference: Survey of Oph, Sept-Oct,2010

61 The Tilted Disc and Glaucoma Assessment Clinical assessment of the optic disc and nerve layer is an important method to diagnose and monitor the progress of glaucomatous optic neuropathy but is often difficult in eyes with tilted discs Comment: Eyes with tilted discs have a different distribution of NFL thickness compared with normal eyes, with the peak of the superior half of the temporally tilted disc shifted temporally and the superior peak of the inferiorly tilted disc blunted. These characteristics should be considered when applying OCT to the interpretation of NFL measurements in eyes with tilted discs. Anomalous ONH anatomy can skew clinical assessment Reference: Archives of Ophthalmology, January 2010

62 ONH Hemorrhage Highly specific for glaucoma Commonly inferotemporal in POAG Commonly superotemporal in NTG Prevalence higher in NTG (20-35%) Disc hemorrhages may precede a VF defect or a change in nerve head Ominous sign in glaucoma patients Associated with aspirin use and diabetes (Ophthalmology 09/04) Among glaucomatous eyes receiving treatment, those with a larger baseline MD and older age had a faster rate of VF loss after a DH developed. There is no association between CCT and the later development of DH. Recurrence of DH during follow-up was not associated with a fast rate of VF loss in this study. (Ophthalmology, January 2010)

63 Parapapillary Atrophy (PPA) Beta-zone parapapillary atrophy and disc hemorrhage are known risk factors for glaucomatous progression. In areas of beta-zone PPA, retinal pigmented epithelium and photoreceptors are absent. About 75% of eyes with a disc hemorrhage had parapapillary atrophy. Since disc hemorrhages are transient, PPA may emerge as a stronger predictor of progression. Glaucoma Today, September 2009

64 Beta-Zone in Glaucoma Analysis Beta-Zone PPA is an important risk factor for glaucoma progression. Eyes with beta-zone PPA reach progression end points more rapidly and have faster global rates of progression. ( db/year vs db/year without PPA) There is a 62% frequency of beta-zone PPA in chronic POAG patients and 15% frequency in normal patients. The presence of beta-zone PPA is a more important marker to gauge for visual field progression than the size of the beta-zone PPA. Ophthalmology, May 2010

65 Parapapillary Atrophy Beta zone Width of beta zone inversely correlates with rim width at same area Larger beta zone thinner rim Progression of beta zone associated with progressive glaucoma

66 Asymmetric Optic Nerves Rule out trauma by Hx, and do gonioscopy Rule out unilateral, chronic, uveitis; pigment dispersion and pseudoexfoliation. Compare corneal pachymetry Pursue the usual glaucoma work-up Remember: Intereye deviations on C/D ratios of 0.2 or less are usually physiological Examine family members to look for traits Reference: Glaucoma Today. September/October 2007

67 Incidence of Clinical Characteristics of Childhood Glaucoma Conclusion: The incidence of childhood glaucoma in this population was 2.29 per 100,000 residents younger than 20 years or 1 per 43,575 residents younger than 20 years. Acquired and secondary forms of glaucoma were the most common, whereas congenital and juvenile glaucoma were rare. Reference: E Aponte et al. Archives of Ophthalmology April 2010.

68 Suspicious Cupping in Children Normal tension glaucoma is seen in older adults A glaucomatous process in childhood without an associated rise in IOP is extremely rare and should be a diagnosis of exclusion. Examine several family members to see if suspicious cupping is merely a family trait. Reference: Glaucoma Today. January/February, 2009.

69 Diagnosing and Managing Ocular Hypertension in Teenagers Juvenile OAG is a rare form of glaucoma that accounts for only approximately 0.2% of glaucoma cases. Teenagers with OHT should be monitored or, if their risk is high enough, should be treated for potential progression to JOAG. Risk factors include male gender, myopia, and a positive family history for glaucoma. Reference: Shai M and Feldman R. Diagnosing and Managing Ocular Hypertension in Teenagers. Glaucoma Today. January/February 2009.

70 Optic Nerve Drusen (OND) and VF Defects Exclusively a disease of Caucasian individuals B-scan ultrasound is the gold standard of Dx Can be unilateral in about 25% of patients Most patients are asymptomatic, but Approx. 75% may have significant VF defects Get 30-2 baseline field on patients with OND Follow every year or two with serial VF Reference: AJO, February 2006

71 Optic Nerve Head Drusen and Glaucoma Differentiating visual field changes due to optic disc drusen from those caused by glaucomatous damage is difficult if not impossible. Nerves crowded by large drusen are more susceptible to damage and monitoring and lowering of IOP should by undertaken upon the documentation of RNFL thinning with visual field progression. Im and Herndon, Glaucoma Today, January/February 2005