NIIOS. Cornea Specialist, Melles Cornea Clinic, NIIOS, Rotterdam, the Netherlands Naval Hospital, Athens, Greece VASILIS S.

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1 Cornea Specialist, Melles Cornea Clinic, NIIOS, Rotterdam, the Netherlands Naval Hospital, Athens, Greece

2

3 Goldman applanation tonometry is still the gold standard for measuring IOP, but its accuracy is influenced by multiple factors CCT IOP how much? which formula? Only CCT? Rigidity? Always correct?

4 Corneal edema IOP Corneal scarring IOP Technique (eg pushing the eyelid)

5 Goldman Applanation Tonometry (GAT) Dynamic Contour Tonometry (DCT) Pascal TonoPen (Reichert) Non Contact Tonometry (NCT) Pulsair (Keeler) Ocular Response Analyzer (ORA) Ocular Blood Flow (OBF)

6 valid and reliable technique to be used in primary eye care easier to use does not transmit infectious diseases not necessary to use anesthetic or staining eye drops

7 (Keeler Pulsair NCT): effective in the identification of postoperative ocular hypertension with a high degree of sensitivity and specificity and good patient compliance statistically significant tendency to overestimate the GAT Vernon et al. Br J Ophthalmol 1989 reliability and reproducibility - No statistically significant differences Bonomi et al. Graefes 1991

8 (Reichert AT550 NCT): IOP values clinically comparable with GAT - validates this NCT not only for screening of IOP but to follow-up glaucomatous patients Jorge et al. Ophthalmic Physiol Opt 2003

9 Non-contact tonometry can be performed with sufficient accuracy over a soft lens on condition: lens center thickness is < 0.30 mm power is < +3D Patel et al. Cont Lens Anterior Eye 2004

10 positive correlation between CCT and IOP measurement GAT increases by 0.4 mmhg / 10μm NCT increases by 0.6 mmhg / 10μm Wangsupadilok et al. J Med Assoc Thai 2011 NCT: overestimates in treated glaucomatous eyes Vincent et al. Clin Experiment Ophthalmol 2012

11 GAT 0.28 mmhg / 10μm Tono-Pen 0.31 mmhg / 10μm OBF 0.38 mmhg / 10μm NCT (Canon TX-10) 0.46 mmhg / 10μm tendency of NCT to overestimate GAT in eyes with thicker corneas Tonnu et al. Br J Ophthalmol 2005

12 Tono-Pachymeter NT530P (Nidek) overestimated the IOP compared with GAT by 1.3 mmhg Schiano Lomoriello et al. Graefes 2011

13 GAT and NCT significant correlated with CCT DCT did not correlate with CCT DCT correlates with GAT and NCT with ~ 3mmHg overestimation Corneal curvature and Axial length do not affect measurements Ito et al. J Glaucoma 2012 DCT drift in the probe measurements? - calibration? (unpublished data)

14 patients with FED : CCT IOP of 0.18 mm Hg/10 μm (GAT), 0.15 mm Hg/10 μm (Tono-Pen) patients with Kconus and after PK : No significant effect of CCT Browning et al. BJO 2004

15 model of an artificial anterior chamber + Intracameral pressure (ICP) adjusted manometrically to mmhg icare, Tono-Pen XL, GAT and ORA NOT dependent on CCT tonopen and icare overestimated by 3-4mmHg at 10mmHg ORA: accurate only at normal" ICP levels; max difference of 2.6mmHg at 30mmHg ICP>30mmHg IOP corneal hysteresis Tono-Pen XL and the icare yielded the most accurate ICP values contact area with the cornea dependence from corneal biomechanical properties Neuburger et al. J Glaucoma 2013

16 In post-pk eyes with >3.00 D of astigmatism or with irregular astigmatism the mean of two readings taken with GAT in the steepest and flattest axis Pandav et al. Ophthalmology 2002

17 Kconus Pellucid PK DCT is designed to measure IOP independent of corneal thickness, corneal curvature and ocular rigidity DCT gave significantly higher IOP readings than GAT Ozbec et al. Cornea 2006

18 GAT DCT PK, Kconus, scars, dystrophies, BK successful measurement of IOP was only possible in 98.2% when using the GAT and in 73.1% with the DCT The agreement between the methods was clinically acceptable in corneal dystrophy and keratoconus but poor in eyes after keratoplasty Rosentreter et al. Cornea 2013

19 GAT TonoPen DCT ORA Prospective cross-sectional DCT: +2mmHg ORA: +6mmHg, least agreement with GAT No instruments correlated significantly with CCT Only DCT independent of corneal astigmatism TonoPen or DCT are the most suitable alternatives for measuring IOP in PK eyes where GAT readings are difficult to obtain Chou et al. AJO 2012

20 ORA and TonoPen overestimate compared to GAT CCT did NOT correlate to any tonometry CCT may be of less importance than corneal hysteresis (CH) and corneal resistance factor (CRF), perhaps because of the lower modulus of elasticity in these eyes ORA / TonoPen overestimating? GAT underestimating? Fabian et al. AJO 2011

21 PK + GDD (Ahmed) Successful IOP control : Survival: Post-valve surgery doubles the risk of failure of IOP control Almousa et al. Cornea 2013

22 PK + GDD (2-30 months after PK; median, 13 months) Baerveldt, Ahmed, Krupin Positioning: 75% in the AC, 25% in the vitreous cavity Successful IOP control: 89% (GDD in AC), 100% (GDD in vitreous) 48 % (GDD in AC), 83% (GDD in vitreous) Arroyave et al. Ophthalmology 2001

23 DALK (Melles technique) Kconus 81%, herpetic scar 6%, other scar 6%, lattice dystrophy 6% Only steroid induced glaucoma (17%), easily controlled by single-dose Rx. Musa et al. Clin Exp Ophth 2012

24 ORA GAT No significant association between CCT and IOP ORA overestimated IOP Feizi et al. IOVS 2011

25 1y FU PK vs DSAEK Patients who had undergone DSAEK had statistically significant lower IOP throughout 12 months after surgery than those who had undergone PK despite similar use of IOPlowering medications during this time Moisseiev et al. Can J Ophth 2013

26 Glaucoma is a common comorbidity IOP elevation can worsen corneal edema Preexisting glaucoma and steroid-responsive ocular hypertension are significant risk factors for graft rejection Does the artificial increase in corneal thickness IOP readings by GAT

27 Falsely elevated GAT, as expected in thick corneas, was NOT demonstrated after DSEK DCT overestimated by 3-4mmHg compared to GAT Vajaranant et al. AJO 2008 GAT DCT TonoPen in DSAEK Measurements are NOT related to artificially thickened corneas Mawatari et al. Jpn J Ophth 2011

28 changes in corneal biomechanics because of edema, grafted tissue, and subsequent stromal deturgescence affect IOP measurement DSAEK for FED, BK, prior graft failure or rejection Although CCT changes, IOP remains near preop measurements until 3 months Chang et al. Cornea 2010

29 Normal vs FED vs DSAEK for FED ORA (cc IOP) higher than GAT and DCT in all groups (overestimated in FED and post DSAEK) GAT and DCT same between groups CH and CRF are reduced in FED and DSAEK Clemmensen et al. Acta Ophth 2013

30 GAT NCT DCT NCT showed the lowest IOP values, although GAT and NCT showed the smallest intertonometry difference. DCT values were higher than those of NCT or GAT. CCT did NOT correlate with any of the IOP measurements NCT or GAT may be lower than the real IOP after DSEK. Yi et al. Cornea 2013

31 FU 1-5y IOP: 17% (1/5 6% later Rx 3% Trab Nieuwendaal et al. IOVS 2013

32 IOP elevation 29 % and post-dsek glaucoma 12% Steroid induced 18% Patients with pre-existing glaucoma showed a significantly higher risk of developing IOP elevation Only Rx no significant difference in graft failure rates between cases with or without pre-existing glaucoma and with or without post-dsek glaucoma Maier et al. Graefes 2013

33 DSAEK + preexisting glaucoma (60% 1med, 30% trab) 17% failed in 12m 62% additional Rx 28% trab in 9m DSAEK combined with other OR 18x higher risk Quek, Tan, Mehta AJO 2011

34 Interface after DSEK Interface after DMEK

35 20/40 (0.5) 20/20 (1.0) Secondary DMEK after DSEK

36 No reliability issue normal corneal anatomy Stromal deswelling

37 GAT is not going anywhere anytime soon. It is a 60-year-old technology and it s ingrained in what we do! Leon Herndon