changes-foveal-fixation-axis-position-between-seated-supine-postures

Changes in Foveal Fixation Axis Position Between Seated and Supine Postures and Their Potential Applications in Refractive Surgery

The correct centration of the ablation in laser refractive surgery is an unresolved classic challenge. This is usually performed at the pupillary center ...

Aston University

Presbyopia is an age-related eye condition where one of the signs is the reduction in the amplitude of accommodation, resulting in the loss of ability to change the eye's focus from far to near. It is the most common age-related ailments affecting everyone around their mid-40s. Methods for the correction of presbyopia include contact lens and spectacle options but the surgical correction of presbyopia still remains a significant challenge for refractive surgeons. Surgical strategies for dealing with presbyopia may be extraocular (corneal or scleral) or intraocular (removal and replacement of the crystalline lens or some type of treatment on the crystalline lens itself). There are however a number of limitations and considerations that have limited the widespread acceptance of surgical correction of presbyopia. Each surgical strategy presents its own unique set of advantages and disadvantages. For example, lens removal and replacement with an intraocular lens may not be preferable in a young patient with presbyopia without a refractive error. Similarly treatment on the crystalline lens may not be a suitable choice for a patient with early signs of cataract. This article is a review of the options available and those that are in development stages and are likely to be available in the near future for the surgical correction of presbyopia.

A review of the surgical options for the correction of presbyopia.

To compare surgical parameters among eyes undergoing laser-assisted cataract surgery (LACS) using different lens fragmentation patterns (LFP).

Comparison of surgical parameters using different lens fragmentation patterns in eyes undergoing laser-assisted cataract surgery.

The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.

CLEAR - Medical use of contact lenses.

To understand the views of contact lens (CL) practitioners across the globe regarding what they perceive as opportunities and threats in CL practice.

Opportunities and threats to contact lens practice: A global survey perspective.

To investigate eye care practitioners' attitudes and perceptions toward potential interventions that can enhance contact lens (CL) practice across the world, and how this is influenced by their practice setting.

Differences in Practitioner Experience, Practice Type, and Profession in Attitudes Toward Growing Contact Lens Practice.

To determine the changes in keratometry measurements and refraction in patients having the thermo-mechanical periorbital skin treatment, Tixel®, to treat dry eye disease (DED).

Impact of thermo-mechanical skin treatment on refraction and keratometry in patients with dry eye disease and the implications for cataract surgery.

The aging eye undergoes the same progressive crosslinking which occurs throughout the body, resulting in increased rigidity of ocular connective tissues including the lens and the sclera which impact ocular functions. This offers the potential for a scleral treatment that is based on restoring normal biomechanical movements. Laser Scleral Microporation is a laser therapy that evaporates fractional areas of crosslinked tissues in the sclera, reducing ocular rigidity over critical anatomical zones of the accommodation apparatus, restoring the natural dynamic range of focus of the eye. Although controversial and challenged, an alternative theory for presbyopia is Schachar's theory that suggests a reduction in the space between the ciliary processes and the crystalline lens. Widening of this space with expansion bands has been shown to aid near vision in people with presbyopia, a technique that has been used in the past but seems to be obsolete now. The use of drugs has been used in the treatment of presbyopia, either to cause pupil miosis to increase depth of focus, or an alteration in refractive error (to induce myopia in one eye to create monovision). Drugs and laser ablation of the crystalline lens have been used with the aim of softening the hardened lens. Poor nutrition and excess exposure to ultraviolet light have been implicated in the onset of presbyopia. Dietary nutritional supplements, lifestyle changes have also been shown to improve accommodation and the question arises whether these could be harnessed in a treatment for presbyopia as well.

BCLA CLEAR presbyopia: Management with scleral techniques, lens softening, pharmaceutical and nutritional therapies.

Antibiotic eyedrops typically require frequent instillation due to the eye's defensive mechanisms limiting drugs from reaching target sites. This may risk patient non-adherence and treatment inefficacy. The aim of this study was to develop a biocompatible and fully soluble ocular film insert to enhance the delivery of levofloxacin, as well as the handling procedure for its administration; based on the anatomical dimensions and physiological conditions of the human eye. Inserts were prepared by solvent casting method, using HPMC, sodium alginate, gelatin, PEG 400, and levofloxacin solution, and characterised for various physicochemical properties (e.g., uniformity of weight and thickness, loss on dryness, swelling index, water uptake and surface pH). Mechanical properties were assessed and compared against a commercially available buccal film formulation. Uniformity of content and release profile of inserts were assessed by means of a validated analytical method. Antibacterial effectiveness was studied by adapted disc diffusion method on Staphylococcus aureus and Pseudomonas aeruginosa. The formulation including HPMC E15 (1250 mg), low viscosity sodium alginate (750 mg), type A gelatin (250 mg) and PEG 400 (2.5 mL) and 0.1% levofloxacin solution, resulted in high quality inserts, exhibiting uniformity of mass, thickness, and levofloxacin content, that comply with Pharmacopeial standards. Inserts were able to withstand unilinear and repeated mechanical stresses, suggesting suitability for manipulation linked to eye administration. The fully soluble levofloxacin-loaded inserts exhibited good physicochemical and mechanical characteristics, indicating good compatibility with ocular environment and administration procedure. Consistent levofloxacin content and biphasic release pattern showed immediate and sustained antimicrobial efficacy, consistently above the minimum inhibitory concentrations for the model species tested. This work also presents an experimental framework that can be adapted for designing and testing ocular drug delivery systems accounting for anatomical and physiological characteristics of the eye.

Development and evaluation of ocular antibiotic-loaded soluble film inserts.

From evidence to action: why does it take so long for clinical practice to adapt?

 Fluorescein break-up time (FBUT) is commonly used to assess tear film stability. However, the instillation of fluorescein destabilises the tear film, impacting validity and clinical applicability, while the subjective nature and variation in volume and concentration reduces repeatability. Non-invasive break-up time (NIBUT) offers an alternative method with less potential bias. Normal tear break-up time is conventionally accepted as 10 seconds (s); however, FBUT is expected to be lower than NIBUT. This study was designed to compare FBUT and NIBUT values in a pre-operative refractive surgery population, where diagnosis of dry eye disease may alter the risk-benefits ratio and contraindicate surgical procedure(s). Improved understanding of the relationship between these two methods will aid appropriate pre-operative patient counselling and consent.  Data from consecutive participants presenting to a private ophthalmology clinic, for initial refractive surgery pre-operative assessment, were analysed. NIBUT and FBUT were performed. Paired and unpaired comparisons were made using the Wilcoxon signed-rank and Mann-Whitney U tests, respectively, and relationships with demographics were explored using Spearman's rank correlation coefficient.  Median and interquartile range (IQR) for the first NIBUT was 12.5 s (7.0-18.0 s) and 14.2 s (9.4-18.0 s) for the right and left eyes, respectively. Median and IQR for the average NIBUT was 14.0 s (6.9-18.0 s) and 14.6 s (10.1-18.0 s) for the right and left eyes, respectively. Median and IQR for FBUT was 7 s (5-8 s) and 6 s (5-8 s) for the right and left eyes, respectively. There was a statistically significant difference between NIBUT and FBUT ( < 0.001).  The findings suggest that the commonly used diagnostic threshold of 10 s cannot be uniformly applied to both FBUT and NIBUT, as FBUT systematically underestimates tear stability.

Article	Year
A review of the surgical options for the correction of presbyopia. The British journal of ophthalmology\| PubMed ID: 25908836	2016
Comparison of surgical parameters using different lens fragmentation patterns in eyes undergoing laser-assisted cataract surgery. International ophthalmology\| PubMed ID: 30830545	2019
CLEAR - Medical use of contact lenses. Contact lens & anterior eye : the journal of the British Contact Lens Association\| PubMed ID: 33775381	2021
Opportunities and threats to contact lens practice: A global survey perspective. Contact lens & anterior eye : the journal of the British Contact Lens Association\| PubMed ID: 34426063	2021
Differences in Practitioner Experience, Practice Type, and Profession in Attitudes Toward Growing Contact Lens Practice. Eye & contact lens\| PubMed ID: 35971228	2022
Impact of thermo-mechanical skin treatment on refraction and keratometry in patients with dry eye disease and the implications for cataract surgery. Contact lens & anterior eye : the journal of the British Contact Lens Association\| PubMed ID: 38594154	2024
BCLA CLEAR presbyopia: Management with scleral techniques, lens softening, pharmaceutical and nutritional therapies. Contact lens & anterior eye : the journal of the British Contact Lens Association\| PubMed ID: 39098809	2024
Development and evaluation of ocular antibiotic-loaded soluble film inserts. Contact lens & anterior eye : the journal of the British Contact Lens Association\| PubMed ID: 39674697	2025
From evidence to action: why does it take so long for clinical practice to adapt? Contact lens & anterior eye : the journal of the British Contact Lens Association\| PubMed ID: 40473551	2025
Comparing Non-Invasive and Fluorescein Tear Break-Up Time in a Pre-Operative Refractive Surgery Population: Implications for Clinical Diagnosis. Journal of clinical medicine\| PubMed ID: 40869620	2025

Raquel Gil-Cazorla

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