Alvaro E. Montero

C. Oliveira

Compañ

J.M. González-Méijome

Jaynes

M. Aguilella-Arzo

Michaud

S.C. Peixoto-de-Matos

Sergio Mollá

Vicente Compañ

Contact Lens and Anterior Eye

Compañ, Vicente

Aguilella-Arzo, Marcel

Montero, Alvaro E.

Mollá, Sergio

Oliveira, C.

Peixoto de Matos, S.C.

González Méijome, J.M.

Repositori Institucional de la Universitat Jaume I

Comments to paper entitled: Predicting scleral GP lens entrapped tear layer oxygen tensions  (Letter)

Compañ Moreno, V.; Aguilella-Arzo, M.; Montero Reguera, ÁE.; Mollá Romano, S.; Oliveira, C.; Peixoto-De-Matos, SC.; Gonzalez-Meijome, JM. (2015). Comments to paper entitled: Predicting scleral GP lens entrapped tear layer oxygen tensions. Contact Lens and Anterior Eye. 38(5). doi:10.1016/j.clae.2015.07.001S39138

Compañ Moreno, Vicente

Aguilella-Arzo, Marcelo

Montero Reguera, Álvaro Enrique

Mollá Romano, Sergio

Peixoto-de-Matos, Sofia C.

Gonzalez-Meijome, J. M.

RiuNet

Comments to paper entitled: Predicting scleral GP lens entrapped tear layer oxygen tensions

Compañ-Moreno, V.

Oliveira, Cristina

Matos, Sofia Cláudia Peixoto

González-Méijome, José Manuel

Universidade do Minho: RepositoriUM

Contact Lens and Anterior Eye 38 (2015) 391Letter to the EditorContents lists available at ScienceDirectContact Lens and Anterior Eyejournal homepage: www.else vie r .com/ locat e/c laeComments to paper entitled: Predicting scleralGP lens entrapped tear layer oxygen tensionsDear Editor,We have read with interest the article authored by Jaynes, J.M.;Edrington, T.B.; Weissman, B.A. recently published in Cont. LensAnterior Eye, (2015; 38: 44–47) entitled “Predicting scleral GPlens entrapped tear layer oxygen tensions ” [1].We found the topic very interesting. However, we think that theconclusion of the authors is not fully supported by their results.The authors alert to the fact that the cornea would suffer hypoxiafor any combination under the best scenario they evaluatedtheoretically (300 microns lens with 140 barrer Dk and 50 micronscorneal clearance). The authors indirectly infer that the corneawould undergo physiological effects. Similar results had alreadybeen found by Michaud et al. [2] and hypothesized that250 microns lens with a Dk higher than 150 barrer and up to200 microns of corneal clearance should be used to minimizecorneal edema. However, none of these two studies providedclinical measures of edema.Having been working in this topic for the last 4 years we admitthat this is at a ﬁrst glance a logical thought. Indeed, when we ﬁrsttried to publish our results back in 2011, reviewers raised thequestion whether such hypothesis would be veriﬁed consideringthe apparent absence of hypoxia in the clinical setting. Then westarted a clinical pilot study to demonstrate the relationshipbetween post-lens tear ﬁlm thickness and physiological stress.Meanwhile, Michaud et al. [2] published their results, whoalready anticipated the results shown in the present study [1]. Bothused constant oxygen consumption for the whole cornea whichdoes not allow to estimate the accurate concentration of oxygen atdifferent levels within the eye. The readers could ﬁnd theseestimations in our previous work [3]. Looking for a directcomparison between the three studies we can report the partialpressure of oxygen for 300–350 lens thickness (Dk = 100 barrer)and post-lens tear ﬁlm of 300–350 microns. Michaud’s resultswould provide about 15 mmHg while Compan’s would predictabout 23 mmHg. Extrapolated data from Jaynes results wouldrender about 24 mmHg very close to our previous predictions.The outcomes from our clinical pilot study conﬁrmed thatedema (as an indirect sign of hypoxia stress) would indeed behttp://dx.doi.org/10.1016/j.clae.2015.07.0011367-0484/ã 2015 British Contact Lens Association. Published by Elsevier Ltd. All righPlease cite this article in press as: V. Compañ, et al., Comments to paptensions, Contact Lens & Anterior Eye (2015), http://dx.doi.org/10.1016/inversely related with the post-lens tear ﬁlm. Our clinical datashowed that edema would raise from 2.5 to 5% which might beconsidered clinically acceptable. Several mechanisms that arebeyond the scope of this letter could result in a lower edemaresponse than that expected from the theoretically predicteddistribution of oxygen through the cornea.References[1] J.M. Jaynes, T.B. Edrington, B.A. Weissman, Predicting scleral GP lens entrappedtear layer oxygen tensions, Cont. Lens Anterior Eye 38 (1) (2015) 44–47.[2] L. Michaud, E. van der Worp, D. Brazeau, R. Warde, C.J. Giasson, Predictingestimates of oxygen transmissibility for scleral lenses, Cont. Lens Anterior Eye35 (6) (2012) 266–271.[3] V. Compañ, C. Oliveira, M. Aguilella-Arzo, S. Mollá, S.C. Peixoto-de-Matos, J.M.González-Méijome, Oxygen diffusion and edema with modern scleral rigid gaspermeable contact lenses, Invest. Ophthalmol. Vis. Sci. 55 (10) (2014) 6421–6429.Vicente Compañ*Departamento de Termodinámica Aplicada, ETSII, UniversidadPolitécnica de Valencia, SpainM. Aguilella-ArzoDepartamento de Física aplicada, Universitat Jaume I, 12080 Caste-llón, SpainAlvaro E. MonteroSergio MolláDepartamento de Termodinámica Aplicada, ETSII, UniversidadPolitécnica de Valencia, SpainC. OliveiraS.C. Peixoto-de-MatosJ.M. González-MéijomeClinical & Experimental Optometry Research Lab (CEORLab), Centerof Physics (Optometry), School of Sciences, University of Minho, Braga,Portugal* Corresponding author. Fax: +34 963877329.E-mail address: vicommo@ter.upv.es (V. Compañ).Received 14 April 2015Received in revised form 15 May 2015Accepted 2 July 2015ts reserved.er entitled: Predicting scleral GP lens entrapped tear layer oxygenj.clae.2015.07.001

Comments to paper entitled "Predicting scleral GP lens entrapped tear layer oxygen tensions"

Crossref

Compañ Moreno, V.; Aguilella-Arzo, M.; Montero Reguera, ÁE.; Mollá Romano, S.; Oliveira, C.; Peixoto-De-Matos, SC.; Gonzalez-Meijome, JM. (2015). Comments to paper entitled: Predicting scleral GP lens entrapped tear layer oxygen tensions. Contact Lens and Anterior Eye. 38(5). doi:10.1016/j.clae.2015.07.00139138

 Document downloaded from:  This paper must be cited as:                  The final publication is available at   Copyright  Additional Information  http://dx.doi.org/10.1016/j.clae.2015.07.001http://hdl.handle.net/10251/63826ElsevierAguilella-Arzo, M.; Compañ Moreno, V.; Montero Reguera, ÁE.; Mollá Romano, S.; Oliveira,C.; Peixoto-De-Matos, SC.; Gonzalez-Meijome, JM. (2015). Comments to paper entitled:Predicting scleral GP lens entrapped tear layer oxygen tensions. Contact Lens and AnteriorEye. 38(5). doi:10.1016/j.clae.2015.07.001.Vicente Compañ et al.    Dear Editor,  We have read with interest the article authored by Jaynes, JM; Edrington, TB; Weissman, BA recently published in Cont Lens Anterior Eye, (2015;38:44-7) entitled “Predicting scleral GP lens entrapped tear layer oxygen tensions”.  We found the topic very interesting. However, we think that the conclusion of the authors is not fully supported by their results. The authors alert to the fact that the cornea would suffer hypoxia for any combination under the best scenario they evaluated theoretically (300 microns lens with 140 barrer Dk and 50 microns corneal clearance). The authors indirectly infer that the cornea would undergo physiological effects. Similar results had already been found by Michaud et al (2012) and hypothesized that 250 microns lens with a Dk higher than 150 barrer and up to 200 microns of corneal clearance should be used to minimize corneal edema. However, none of these two studies provided clinical measures of edema.    Having been working in this topic for the last 4 years we admit that this is at a first glance a logical thought. Indeed, when we first tried to publish our results back in 2011, reviewers raised the question whether such hypothesis would be verified considering the apparent absence of hypoxia in the clinical setting. Then we started a clinical pilot study to demonstrate the relationship between post-lens tear film thickness and physiological stress.   Meanwhile, Michaud et al. (2012) published their results, who already anticipated the results shown in the present study (Jaynes et al, 2015). Both used a constant oxygen consumption for the whole cornea which does not allow to estimate the accurate concentration of oxygen at different levels within the eye. The readers could find these estimations in our previous work (Compan et al. 2014). Looking for a direct comparison between the three studies we can report the partial pressure of oxygen for 300 to 350 lens thickness (Dk=100 barrer) and post-lens tear film of 300 to 350 microns. Michaud’s results would provide about 15 mmHg while Compan’s would predict about 23 mmHg. Extrapolated data from Jaynes results would render about 24 mmHg very close to our previous predictions.   The outcomes from our clinical pilot study confirmed that edema (as an indirect sign of hypoxia stress) would indeed be inversely related with the post-lens tear film. Our clinical data showed that edema would raise from 2.5 to 5% which might be considered clinically acceptable. Several mechanisms that are beyond the scope of this letter could result in a lower edema response than that expected from the theoretically predicted distribution of oxygen through the cornea.      References  Jaynes JM, Edrington TB, Weissman BA. Predicting scleral GP lens entrapped tear layer oxygen tensions. Cont Lens Anterior Eye. 2015;38(1):44-7.  Michaud L, van der Worp E, Brazeau D, Warde R, Giasson CJ. Predicting estimates of oxygen transmissibility for scleral lenses. Cont Lens Anterior Eye.  2012;35(6):266-71.  Compañ V, Oliveira C, Aguilella-Arzo M, Mollá S, Peixoto-de-Matos SC, González-Méijome JM. Oxygen diffusion and edema with modern scleral rigid gas permeable contact lenses. Invest Ophthalmol Vis Sci. 2014;55(10):6421-9. 

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Comments to paper entitled "Predicting scleral GP lens entrapped tear layer oxygen tensions"

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