Laser Corneal Research Articles

Advantages of Surface Ablation in Excimer Laser Surgery

In this article, we review the advantages of corneal laser surface surgery to explain the current trend toward this technique. The excimer laser in corneal surface surgery can be used for two reasons. On the one hand, to correct a refractive error by photorefractive keratectomy (PRK) and its two variants; Laser epithelial keratomileusis (LASEK) and Epithelial Laser-assisted in situ keratomileusis (Epi-lasik).
 On the other hand, it is used to perform superficial corneal capacities photoablation, among other uses, by Phototherapeutic keratectomy (PTK).
 PRK is regaining popularity thanks to its better safety profile, mitomycin C usage and improvement of photoablation profiles. Lasek and Epilasik are less frequently performed nowadays.
 PTK is an important element in the techniques used to improve visual acuity in a wide range of corneal conditions such as corneal scars, recurrent erosion syndrome and corneal dystrophies.

Chinese Expert Consensus on Perioperative Medication in Laser Corneal Refractive Surgeries (2019).

Laser corneal refractive surgery has become an important treatment to correct ametropia in recent years. Rational medication in the perioperative period is essential to ensure the success of the surgery and to reduce complications. However, in this area there has been no consistent understanding and unified application guide across the world. Experts in Refractive Surgery Group, Ocular Microcirculation Branch of Chinese Society of Microcirculation who are specialized in keratology and optometry had initiated extensive and rigorous discussions and reached a consensus on appropriate medication before, during and after the refractive surgeries. The consensus covers a broad spectrum of commonly used ophthalmic solutions, provides recommendations of routine and enhanced medication on prevention and management of adverse reactions and complications related to the laser corneal refractive surgeries. We hope the consensus serves as a standard perioperative medication regimen for ophthalmologists, helps to ensure the safety and effectiveness of laser corneal refractive surgeries, and improves the quality and outcome of the refractive surgeries.

Diabetic neuropathy: A focus on small fibres.

Diabetic peripheral neuropathy (DPN) is diagnosed too late, which contrasts with our approach for diabetic retinopathy and nephropathy, where incipient disease is detected early enabling timely treatment. The 10-g monofilament and a foot exam are the commonly used methods for screening diabetic neuropathy, but this primarily identifies moderate to severe diabetic neuropathy. Small fibres are damaged early and are associated with the development of painful diabetic neuropathy, foot ulceration, and Charcot foot. Tests of small fibre damage include thermal thresholds, microneurography, evoked potentials, sudomotor function, laser Doppler flare, skin biopsy, and corneal confocal microscopy. Measures of small fibre damage and repair may be key to the assessment of efficacy in clinical trials of disease modifying therapies for diabetic neuropathy.

Analysis of corneal stromal roughness after iFS 150 kHz and LenSx femtosecond LASIK flap creation in porcine eyes.

To describe and compare the stromal bed roughness obtained after laser in situ keratomileusis (LASIK) flap creation using a corneal femtosecond laser platform (iFS 150) and a "dual" femtosecond (FS) laser platform (LenSx). This ex vivo experimental study was conducted in an animal model using 12 freshly enucleated porcine eyes, six with each femtosecond laser. The standard laser treatment parameters were used for the experiment. After LASIK flap creation, the corneal stromal roughness was assessed using atomic force microscopy (AFM) in contact mode immersed in liquid. In each sample, surface measurements were obtained in 60 regions of six eyes per FS laser in 10 20 × 20-micron areas of the central corneal stroma at 512 × 512-point resolution. The surface roughness was measured and the root-mean-square (RMS) values of the roughness were obtained. The mean RMS ± standard deviation values were 430 ± 150 nm for the corneal femtosecond laser platform and 370 ± 100 nm for the dual FS laser platform (P < 0.011). In this experimental study with AFM, we found smoother stromal beds after LASIK flap creation with LenSx compared to iFS 150 kHz. Further studies are needed to understand visual implications of the differences found.

Presbyopic refractive lens exchange with trifocal intraocular lens implantation after corneal laser vision correction: Refractive results and biometry analysis

To evaluate the refractive and biometry results of presbyopic refractive lens exchange (RLE) with trifocal intraocular lens (IOL) implantation in eyes with previous myopic or hyperopic corneal laser vision correction (LVC). Memira AS, Norway, Sweden, and Denmark. Retrospective case series. The refractive results included the manifest refraction spherical equivalent, uncorrected near (UNVA) and distance (UDVA) visual acuities, corrected distance visual acuity, safety, efficacy, and precision. The biometry analysis included the refractive prediction error (RPE), median absolute error (MedAE), and percentage of eyes within a certain RPE range for the formulas from the American Society of Cataract and Refractive Surgery (ASCRS) online calculator. The study comprised 241 eyes. Six months postoperatively, 60.0% of eyes were within ±0.25 diopter (D), 80.9% within ±0.50 D, and 97.9% within ±1.00 D of emmetropia. There were no statistical differences in the mean monocular UDVA (0.87 ± 0.20 [SD]), safety index (0.98 ± 0.09), or efficacy index (0.81 ± 0.18) between the myopic ablation group and hyperopic ablation group. Binocularly, 85% of patients had simultaneous UDVA and UNVA of 0.9 or better and Jaeger 3, respectively. The ASCRS online calculator formulas gave different performances for previous myopic and hyperopic ablation profiles. Using optimized constants and nomogram for correcting the mean RPE improved the MedAE. Presbyopic RLE was safe and effective in selected cases with a history of LVC. The use of optimized IOL constants and nomograms can improve the refractive precision of lens-based refractive surgery.

Thygeson’s superficial punctate keratitis

Thygeson's superficial punctate keratitis (TSPK) is a chronic, bilateral epithelial keratitis. Dr Philips Thygeson first reported TSPK in 1950. Although the etiology of TSPK remains unknown, it has been reported to be associated with viral and autoimmune pathologies. The disease course is characterized by exacerbations and remissions. The classical finding on slit lamp examination is the presence of distinctive coarse, raised, oval-shaped corneal epithelium lesions. Patients commonly present with ocular irritation and rarely with reduced visual acuity. Topical corticosteroids are the mainstay of treatment. Other less commonly used treatments included topical cyclosporine, contact lenses and corneal laser.

Importance of the precise and personalized selection of laser corneal refractive surgery

Laser corneal refractive surgery is currently the most mainstream surgery to correct refractive errors.In recent years, the laser corneal refractive surgery has been developed rapidly in China.Femtosecond laser small incision lenticule extraction (SMILE) and the femtosecond laser flap laser in situ keratomileusis (LASIK) are greatly improving the safety of the laser lamellar corneal refractive surgery, and trans-epithelial photorefractive keratectomy (Trans PRK) is also taking the surface ablation of excimer laser to a new level.Compared with traditional excimer laser corneal refractive surgery, the above methods are more safe, stable and reliable.Trans PRK, SMILE and femtosecond flap LASIK combined with riboflavin corneal cross-linking provides a safe guarantee for the myopic patients with thin cornea and abnormal corneal topography.As rapid progress and upgrading of laser corneal refractive surgery technologies, selection of operation methods is a new challenge.Ophthalmologists should comprehensively evaluate the corneal anatomical characteristics, individual needs of patients, performance of operating equipment and indications of different surgeries to pay more attention to the precise and personalized selection of laser corneal refractive surgery to improve the postoperative visual quality of patients with ametropia. Key words: Lasers, excimer/therapeutic use; Corneal refractive surgery; Visual quality; Personalize

Советы и рекомендации по фемтосекундной лазерной хирургии роговицы

Советы и рекомендации по фемтосекундной лазерной хирургии роговицы

Pressure wave propagation effects in the eye after photoablation

A transient pressure wave created in photoablation-based laser corneal refractive surgery propagates along the optical axis of the eye from the cornea toward the fundus. Along its path, it is attenuated, reflected several times at tissue interfaces, focused due to the spherical shape of the cornea, and partially phase-converted to a tensile wave after passing the acoustic focus. Employing the numerical acoustic eye model, the dynamics of the acoustic focusing is described in detail. The simulated pressure waveforms are first validated against the existing measurements. Then, the calculated full pressure fields are used to obtain the extreme values of the pressure amplitude at every point within the eye over the whole timespan of interest. Over these pressure maps, various threshold contours obtained from the existing literature are superimposed to help ophthalmologists investigate the consequences of acoustic focusing within the human eye during laser keratorefractive surgery. The comparison indicates that the simulated negative peak pressure values used in the contemporary broad beam and flying spot laser-assisted in situ keratomileusis/photorefractive keratectomy treatments exceed some of the reported threshold values. The critical volume where the thresholds are surpassed is located near the lens-vitreous boundary and extends to the retina for wide beams. The photoablation-induced pressure wave focusing is, therefore, a mechanism that needs to be researched carefully and included in the list of potential risks accompanying refractive laser surgery.

Morphometric Analysis of Corneal Nerves Condition after Laser Keratorefractive Surgery

Purpose: to conduct a morphometric assessment of the corneal nerves state after laser keratorefractive surgery using laser confocal microscopy and the software Liner 1.2S. Patients and methods. 40 eyes of 20 patients received LASIK to correct a mean refractive error of –4.5 ± 1.9 diopters (range, –2.25 to –8.25 diopters). The stroma was ablated with a Teneo Technolas 317P excimer laser. Corneas were examined by laser corneal confocal microscopy (HRT III with Rostock Cornea Module) before and in 1, 3, and 6 months after LASIK. Images were analyzed with software that automatically computes coefficients of anisotropy and orientation symmetry of corneal nerves. Result. At 1 and 3 months after surgery, the center corneal nerves were completely absent. At 1, 3 and 6 months after surgery, the paracentral corneal nerves were detected and the coefficient of anisotropy were statistically significantly reduced compared with the preoperative rates. At 6 months after surgery, both central and peripheral corneal nerves were detected and the coefficient of anisotropy were statistically significantly reduced compared with the preoperative rates. Conclusion. As a result of the study, the central corneal nerves were first detected at 6 months after surgery, whereas the paracentral cornea nerves were detected already after 1 month. At 6 months after surgery, the coefficient of anisotropy in the central of cornea statistically significant decreased compared to the preoperative rates. At all stages of the study after surgery, the anisotropy coefficient in the cornea paracentral statistically significant decreased compared with preoperative.

Efficacy of Care for Blind Painful Eyes.

Pain relief for a blind painful eye often follows an escalating paradigm of interventions. This study compares the efficacy of common interventions. A retrospective chart review of blind painful eye cases was conducted at a single tertiary institution from April 2012 to December 2016. Demographics, etiology, treatment, and pain level were assessed. Among 99 blind painful eyes, 96 eyes initially received medical therapy (topical steroids, cycloplegics, and/or hypotensives), with pain relief in 39% of eyes. Minimally invasive interventions (laser cyclophotocoagulation, retrobulbar injection, or corneal electrocautery) were performed 41 times in 36 eyes, 34 of which had failed medical therapy, and led to pain relief in 75% of eyes. Evisceration or enucleation was performed in 28 eyes, and long-term pain relief was achieved in 100% of eyes. Surgery allowed discontinuation of oral analgesics in 100% of cases versus 20% for minimally invasive therapy (p = 0.005) and 14% for medical therapy (p = 0.0001). Compared with medical therapy, minimally invasive therapy was 2.5 times more likely to achieve lasting pain relief (p = 0.003) and surgical therapy 35.6 times more likely to achieve lasting pain relief (p = 0.011). High initial pain score was associated with nonsurgical treatment failure. Medical therapy provides pain relief in a moderate number of patients with a blind painful eye. When medical therapy fails, minimally invasive therapy and surgical interventions are successively more effective in relieving ocular pain. High initial pain score is a risk factor for nonsurgical therapy failure and may merit an earlier discussion of surgical intervention.

Development of a defined approach for eye irritation or serious eye damage for liquids, neat and in dilution, based on cosmetics Europe analysis of in vitro STE and BCOP test methods

The focus of Cosmetics Europe's programme on serious eye damage/eye irritation is on development of testing strategies and defined approaches for identification of ocular effects of chemicals in the context of OECD's Guidance Document on an Integrated Approach on Testing and Assessment (IATA) for Serious Eye Damage and Eye Irritation.Cosmetics Europe created a comprehensive database of chemicals for which in vitro data are available with corresponding historical in vivo Draize eye data. This database allowed further exploration of the initially proposed strategies from the CON4EI project and to identify opportunities for refinement. The current analysis focused on the development of a defined approach, applicable to liquid non-surfactant chemicals, neat and in dilution, that can distinguish between the three UN GHS categories (Cat. 1, Cat. 2, and No Cat.). Combining the modified-protocol Short Time Exposure (STE) test method (OECD TG 491 with extension to highly volatile substances) with the Bovine Corneal Opacity and Permeability Laser Light-Based Opacitometer (BCOP LLBO) test method in a Bottom-Up approach identified 81.2% Cat. 1, 56.3% Cat. 2, and 85.3% No. Cat correctly, with an NPV of 96.7% and a PPV of 68.6%. Therefore, the performance of the defined approach was better than the standalone test methods.

Results of laser confocal microscopy of the cornea in viral uveitis (a preliminary report)

To evaluate the results of laser corneal confocal microscopy (CCM) in viral uveitis of varying localization. The main study group included 23 patients (23 eyes) diagnosed with unilateral herpesviral uveitis (chorioretinitis), the patients' age varied from 18 to 79 years. The control group comprised 19 healthy volunteers (38 eyes) aged 20 to 75 years. In addition, the paired eyes of the main group patients were examined. In all patients, standard ophthalmologic examination was complemented with CCM performed on the HRT III device with a corneal module, followed by analysis of the course and structure of corneal nerve fibers (CNF) using copyrighted software Liner 1.2. The preliminary results achieved in this study outline the prospects for further research on the state of cornea (in particular, changes in the course and structure of CNF, and the presence of dendritiform cells of Langerhans) with laser CCM in patients with uveitis of various etiologies. These morphological changes also has potential use as diagnostic markers of inflammation of the uveal tract. The main criteria for assessing the state of cornea in viral uveitis include the following: increased tortuosity of CNF, increase in the number and size of Langerhans cells. Further research - in particular, studying the integrated use of diagnostic methods necessary for the verification of viral uveitis, as well as detailed analysis of the history and clinical picture of the disease - is required to substantiate the inclusion of laser confocal microscopy method in the algorithm for the diagnosis of viral uveitis.

An Analysis on the Change Rule of Eyeball's Biological Parameters of Different Types in the Refraction State and Vision Before and After Refraction

The ametropia is the most widespread eye disease for the humans. Wherein, the myopia is the commonest ophthalmological reason influencing the distant vision. The excimer laser corneal refractive surgery has always been an operation mode most widely used in myopic correction operations for a number of years. The laser assisted in-situ keratomi (LASIK) mainly transforms the frontal surface appearance of the cornea to change the corneal refraction power, and its correction effect is influenced by a great many factors such as regression and hydration of cornea. Thus, a lot of surgeons would combine own experience in conducting LASIK myopic correction. The myopic regression would affect the foreseeability, operation effect and stability of corneal refractive surgery, which results in reduction of the patients' visual quality in turn. The pathogenesis still needs further study. The change of lens thickness does not only lead to change in depth of central anterior chamber, but also would cause the change in refractive power of lens, thereby influencing the whole dioptric system of the eyeball. The previous research on postoperative regression was mostly focused on the corneal refraction, while few efforts were put in the changes of lens thickness and refractive power after LASIK.

The Effect of Aging on Nerve Morphology and Substance P Expression in Mouse and Human Corneas.

Aging impairs corneal nerve density and sensitivity. Substance P (SP), a neuropeptide secreted by sensory nerves, regulates nerve morphology and nociception. Here, we investigate the relationship between aging, nerve morphology, and SP expression in mouse and human corneas. SP levels in mouse corneas (wild type and substance P-knockout) and human corneas and tears were quantified with an ELISA assay. Corneal total nerve length (TNL) was measured with whole-mount β3-tubulin immunofluorescence in mouse and in vivo laser corneal confocal microscopy in humans. SP and β3-tubulin stained cross-sections were used to assess the colocalization of SP and nerves in human and mouse corneas. Ocular surface nociception was assessed with a wiping test in mice. SP colocalizes with sub-basal neurons in mice and humans. In WT mice, SP levels decrease with age (P = 0.0045, 8 vs. 52 weeks; P = 0.004, 26 vs. 52 weeks) as well as TNL (P = 0.018, 8 vs. 26 weeks; P = 0.0001, 8 vs. 52 weeks). Knockout mice show a greater TNL reduction (8 vs. 26 weeks, P = 0.0016) than WT mice. In the oldest WT and age-matched KO mice, nociception is impaired (P = 0.007 and P < 0.0001, respectively), and KO mice sensitivity is restored by topical SP treatment. In humans, SP levels are reduced in old subject corneas and correlate, in tears, with age (P = 0.0368); TNL also decreases in older patients (P = 0.0002). Age-associated corneal nerve loss is paralleled by reduction of SP expression in mice and humans. SP promotes the maintenance of normal nerve morphology in the long term and modulates nociception in the cornea.

Carefully performing the phakic intraocular lens implantation for moderate and low myopia

The refractive surgery is improved and updated with time. In recent years, the phakic intraocular lens has been continuously modified and innovated in materials and design. With advantages such as less high-order aberrations, reversible lens and good visual quality, it has led to a new trend of refractive surgery, which attract an increasing number of high myopic persons received phakic intraocular lens implantation instead of corneal refractive surgery, particularly to further expand the applying for moderate and low myopia. This article focuses on the rational selection of moderate and low myopia to receive laser correction vision or phakic lens, and elaborates the different characteristics with advantages and disadvantages of corneal refractive surgery and phakic intraocular lens implantation, which suggest to perform the phakic intraocular lens implantation for moderate and low myopia cautiously and standardize surgical indications strictly. It is necessary to continuously strengthen the standardization and safety of laser corneal refractive surgery and phakic intraocular lens implantation in order to improve the visual quality and satisfaction further for myopic patients in clinic. (Chin J Ophthalmol, 2018, 54: 726-728).

Outcomes of Wavefront-Optimized Laser-Assisted In-Situ Keratomileusis and Photorefractive Keratectomy for correction of Myopia and Myopic Astigmatism over One Year Follow-Up

Background:Laser corneal refractive surgery suits, technology and nomograms are improving with time. This may improve the refractive and visual outcomes of the patients.Objectives:To evaluate the safety, efficacy, stability, and predictability of wavefront-optimized photorefractive keratectomy and Laser-assisted in-situ keratomileusis in patients with myopia and myopic astigmatism over 1-year using WaveLight® EX500 Excimer Laser machine.Methods:In this prospective cohort study, refractive and visual outcomes in 596 eyes (365 patients), either having myopia or myopic astigmatism were assessed. Patients were divided into Two groups: 1) Patients who underwent PRK (53 eyes have myopia and 217 eyes have myopic astigmatism), 2) Patients who underwent LASIK (53 eyes have myopia and 273 eyes have myopic astigmatism).Results:At 12 months postoperatively 94.3% of the myopic patients reached their preoperative best corrected distance visual acuity at the final one year follow up visit post PRK and LASIK. In patients with myopic astigmatism who underwent LASIK and PRK, 95.2%, and 96.3% of the patients reached their preoperative best corrected distance visual acuity at the final one year follow up visit post LASIK and PRK, respectively. The efficacy and safety indices were 1.00 or more for all groups with no eye lost any line of best corrected distance visual acuity.Conclusion:Our study results confirm the excellent efficacy, safety, good predictability and stability of myopia / myopic astigmatism correction by either wavefront- optimized LASIK or PRK over 1-year follow-up without significant differences between them using the WaveLight® EX500 excimer laser system.

Myopic Laser Corneal Refractive Surgery Reduces Interdevice Agreement in the Measurement of Anterior Corneal Curvature.

To investigate interdevice differences and agreement in the measurement of anterior corneal curvature obtained by different technologies after laser corneal refractive surgery. The prospective study comprised 109 eyes of 109 consecutive patients who had undergone laser-assisted in situ keratomileusis (LASIK). Preoperative and postoperative corneal parameters were measured by Scheimpflug imaging (Pentacam), Placido-slit-scanning (Orbscan) and auto-keratometry (IOLMaster). Preoperative and postoperative anterior corneal curvatures (K readings) were compared between devices. Interdevice agreement was evaluated by Bland-Altman analysis. Preoperatively, the difference of K reading for Pentacam-IOLMaster (0.04±0.20 D) was not statistically significant (P=0.059). The differences between Pentacam-Orbscan and Orbscan-IOLMaster were 0.20±0.34 D (P<0.001) and -0.17±0.29 D (P<0.001), respectively. After surgery, no difference was found for Pentacam-Orbscan (-0.05±0.38, P=0.136). The differences between Pentacam-IOLMaster and Orbscan-IOLMaster were 0.13±0.29 D (P<0.001) and 0.19±0.34 D (P<0.001). Preoperative interdevice agreement (95% limit of agreement [LOA]) between Pentacam and Orbscan, Pentacam and IOLMaster, and Orbscan and IOLMaster were 1.31 D, 0.79 D and 1.14 D, respectively. The 95% LOAs decreased to 1.47 D, 1.14 D, and 1.34 D after refractive surgery. Corneal refractive surgery changed the preoperative and postoperative interdevice differences in corneal curvature measurements and reduced interdevice agreement, indicating that the devices are not interchangeable.

Simultaneous Accelerated Corneal Crosslinking and Laser In situ Keratomileusis for the Treatment of High Myopia in Asian Eyes

Background LASIK Xtra is a recently described technique which combines LASIK and accelerated corneal cross-linking(CXL) in the same setting. Its long-term outcome in Asians with high myopia is not well described. Objectives To compare the efficacy, predictability and safety of LASIK Xtra with LASIK in patients with high myopia. Method This is a retrospective study comparing 50 consecutive eyes undergoing LASIK Xtra for the correction of high myopia and/or myopic astigmatism (-6.63 to -15.50 D manifest spherical equivalent) with a matched control group of 50 eyes undergoing LASIK alone for correction of high myopia (-6.00 to -12.25 D manifest spherical equivalent). Mean follow-up was 5.7 months (range, 1.5-13.3 months) for LASIK Xtra and 3.6 months (range, 1.7-4.2 months) for LASIK only. Outcome measures included Uncorrected Distance Visual Acuity (UDVA), Corrected Distance Visual Acuity (CDVA), refraction and intraoperative and postoperative complications. Results At post-operative 3 months, all eyes achieved UDVA of 20/40 or better, and 80.0% of LASIK Xtra eyes achieved UDVA of 20/20 or better, compared to 66.0% of LASIK only eyes (p = 0.115). Efficacy indices were 0.99±0.17 for LASIK Xtra and 0.94±0.17 for LASIK only (p = 0.164). The proportion of eyes within ±0.50 D of attempted correction was 84% in the LASIK only group and 72% in the LASIK Xtra group at post-operative 3 months (p = 0.148). Safety indices were 1.11±0.19 and 1.11±0.18 in the LASIK Xtra and LASIK only groups, respectively (p = 0.735). Conclusion LASIK Xtra achieved comparable safety, predictability and efficacy as LASIK in patients with high myopia. Good refractive stability was attained at 6-12 months. Further long term studies are required to determine whether simultaneous CXL is able to reduce postoperative LASIK keratectasia in high-risk individuals.

Senile eye disease screening program in downtown Wenzhou: intraocular pressure

Objective: To investigate the distribution and related factors of intraocular pressure (IOP) in the screened population aged over 50 years in Wenzhou. Methods: This study included 31 170 community residents aged 50 years or older in Wenzhou undergoing screening from March 2014 to January 2016. Participants underwent a complete ocular examination, including visual acuity, eye-ground photography, slit lamp and standardized measurement of IOP by non-contact tonometry. Subjects who had undergone ocular operation or laser peripheral iridectomy, had glaucoma, corneal or other ocular diseases that could possibly affect the IOP, had an IOP lower than 6 mmHg(1 mmHg=0.133 kPa) and visual acuity less than 0.3, or had monocular IOP values were excluded. The relationship between IOP and various parameters were analyzed. Results: A total of 20 875 subjects (6 902 males and 13 973 females) were enrolled in the current analysis, including 18 677 healthy persons and 2 125 glaucoma suspects, with an average age of (67.3±8.7) years old. The mean IOP (mean±standard deviation) of the healthy population was (13.5±3.0) mmHg (13.4±3.2) mmHg in right eyes and (13.6±3.3) mmHg in left eyes; 2.04% of the left eyes, 1.51% of the right eyes and 2.92% of either eyes of healthy population had an IOP >21 mmHg. The mean IOP in glaucoma suspects was significantly higher than that in the healthy population (P<0.001); 6.78% of the left eyes, 6.16% of the right eyes and 9.65% of either eyes of glaucoma suspects had an IOP >21 mmHg. Men had lower IOPs than women [healthy population: (12.9±3.2) mmHg versus (13.7±3.2) mmHg; P<0.05]. The linear function of IOP (Y) with age (X(1)) and the vertical cup disc ratio (X(2)) was ^Y=15.962-0.043X(1)+0.837X(2)(P<0.05) in the healthy population. Conclusion: The IOP among healthy persons aged over 50 years living in downtown Wenzhou was decreased with age but increased with the vertical cup disc ratio. The IOP in females was higher than that in males. About 3% of the healthy population had an IOP greater than 21 mmHg. (Chin J Ophthalmol, 2018, 54: 586-592).