Year : 2020 | Volume
: 32 | Issue : 3 | Page : 321--322
Sreepury, Balussery PO, Calicut - 673 612, Kerala, India
Sreepury, Balussery PO, Calicut - 673 612, Kerala
|How to cite this article:|
Reshmi S. Journal Review.Kerala J Ophthalmol 2020;32:321-322
|How to cite this URL:|
Reshmi S. Journal Review. Kerala J Ophthalmol [serial online] 2020 [cited 2021 Mar 1 ];32:321-322
Available from: http://www.kjophthal.com/text.asp?2020/32/3/321/304545
Prospective, Randomized, Eye-to-Eye Comparison of a New Silicone Coreal Shield Versus Conventional Bandage Contact Lens After Photorefractive Kepatectomy
Hirabayashi KE, Sales C, Slade SG, Manche EE. Prospective, randomized, eye-to-eye comparison of a new silicone corneal shield versus conventional bandage contact lens after photorefractive keratectomy. J Cataract Refract Surg 2019;45:1782-8 Q 2019 ASCRS and ESCRS.
Photorefractive keratectomy (PRK) is a commonly performed refractive surgery that has equivalent safety and efficacy when compared to laser in situ keratomileusis (LASIK) in treating myopia. Although PRK avoids potential flap-related complications, one disadvantage of PRK is the postoperative healing phase, which is more prolonged and uncomfortable compared with LASIK. Various options for decreasing pain after PRK include the use of bandage contact lenses (BCL), topical anesthetics, topical nonsteroidal anti-inflammatory agents, and oral analgesics.
A contact lens that can offer quicker visual rehabilitation and improved comfort would be a game-changer for PRK. Silicone hydrogel lenses are generally preferred because they have high oxygen permeability. However, there is no definite consensus as to which lens is the superior choice. There is a new silicone corneal shield made by NexisVision which has a thin soft periphery and a thicker and slightly stiffer central optic design to improve postoperative vision. It is composed of a bimodulus, silicone, elastomer material that is highly permeable to oxygen, especially in the area overlying the limbus, to facilitate reepithelialization. The Dk of the material is more than 300, but the shield is thicker than most contact lenses, making its Dk/t 110. It is impermeable to water, which helps minimize the development of corneal edema.
The aim of this study is to compare the new silicone corneal shield with a conventional silicone hydrogel BCL after PRK in terms of uncorrected distance visual acuity (UDVA) and patient-reported outcomes.
This is a prospective randomized cohort study that enrolled 25 participants (50 eyes) undergoing myopic PRK from May 2012 to April 2013. Inclusion criteria included less than 11.0 D of myopia with less than 3.50 D of astigmatism. The use of rigid gas-permeable contact lenses previously was an exclusion criterion. Patients were randomized by ocular dominance to receive either the new silicone corneal shield or a conventional BCL in their dominant eye and the other intervention in the contralateral eye. The UDVA and patient-reported outcomes were measured preoperatively, 1 h after surgery, and at 1, 2, 3, 4, and 7 days postoperatively.
Surgery was done by experienced refractive surgeons. An epithelial scrubber or an alcohol well was used to remove the epithelium. A 6.0-mm optical treatment zone was selected, and Mitomycin C (MMC) 0.02% was applied after ablation for 20 s in all cases. Postoperative medications were topical moxifloxacin 0.5%, topical prednisolone 0.125%, and topical diclofenac 0.1% and oral ibuprofen. A postoperative questionnaire was used to assess patient-reported outcomes.
The new silicone corneal shield group had statistically significant superior mean logMAR UDVA than the conventional BCL group 1 h after the surgery and at 1, 2, 3, 4, and 7 days postoperatively. Eyes treated with the new silicone corneal shield also achieved epithelial closure more frequently by 3 days postoperatively compared with eyes treated with the BCL. However, these patients reported increased symptoms of pain, foreign body sensation, and eyelid heaviness with the shield. Potential explanation is that the new silicone corneal shield is nearly 4 times thicker than a standard BCL, and it has lower absolute oxygen transmissibility. The bulkiness of the lens and the relative hypoxia it induces might explain the increased discomfort experienced as compared with a conventional BCL.
The strengths of this study include its prospective, randomized, contralateral, and controlled nature and the masked nature of the study. The limitations include the lack of validation for the questionnaire and the modest size of the study population.
In summary, postoperative recovery remains the largest drawback of PRK. Although the Nexis silicone corneal shield provides a quicker visual recovery, it is associated with increased symptoms of pain, light sensitivity, foreign body sensation, and tearing when compared with a conventional BCL.
Assessment of Factors Associated With Postoperative Pain After Photorefractive Keratectomy
Palochak CM, Santamaria J, Justin GA, Apsey DA, Caldwell MC, Steigleman WA, et al. Assessment of factors associated with postoperative pain after photorefractive keratectomy. Cornea 2020;39:1215-20.
Photorefractive keratectomy (PRK) is a refractive surgery procedure that uses an excimer laser to reshape the cornea to treat refractive error in patients with myopia, astigmatism, and hyperopia. This correction can reduce or eliminate a patient's need for glasses or contact lenses. PRK reshapes the cornea without the creation of a stromal flap, giving it unique advantages over flap-based procedures, such as laser in situ keratomileusis.
However, PRK has a noted disadvantage of postoperative discomfort and pain. PRK involves manually removing the epithelium, creating an epithelial defect in the ablation zone that contributes to the increased pain experienced by patients postoperatively. Multiple studies have shown that this pain is typically most severe during the first day with peak subjective pain reported at 24 h. For some, this pain can be severe and difficult to control in the early postoperative period. Optimal management of this pain has been extensively researched and debated, with studies proposing a wide array of topical and oral nonsteroidal anti-inflammatory drugs, topical anesthetics, bandage contact lens, or a combination of these modalities.
This study aims to determine what factors contribute to postoperative pain in PRK. This retrospective chart review evaluated patients who underwent PRK in 2016. Anonymized data collected included patient gender, age, and season at the time of surgery, ablation depth, surgeon status (attending vs. resident), topical tetracaine use, and subjective pain scores at postoperative days (PODs) 1 and 7. Average pain scores and amount of pain medication taken were analyzed for each of the previously mentioned variables.
All surgeries were performed by or with the direct supervision by a cornea-trained military ophthalmologist following the same standardized protocol. Postoperative medications included topical moxifloxacin 0.5% drops 4 times a day, fluorometholone acetate drops 4 times a day, preservative-free artificial tears as needed, and oral analgesics. Patients were also given an unopened bottle of topical tetracaine hydrochloride 0.5% with instructions to use only in the event of severe pain that was preventing adequate rest. Patients were followed as per standard protocol on PODs 1 and 7 with assessment of their pain, number of tetracaine drops used, and number of pain pills consumed, verified, and recorded by a trained ophthalmic technician.
Postoperative pain was significantly elevated in patients who used tetracaine on POD 1 and POD 7. These patients were also more likely to take oral pain medication than those who did not use topical tetracaine. Surgeon status, season, gender, and ablation depth showed no significant differences in subjective pain scores.
Limitations of this study are that it was retrospective in nature and that it only recorded pain data from PODs 1 and 7. Furthermore, the 10-point scale was based on an established onsite system that may not be equivalent to more detailed methods and questionnaires for quantifying and qualifying pain.
To conclude, most treated patients have minimal postoperative pain, allowing PRK to continue to be a good and effective option for military patients. Furthermore, oral pain medication should be evaluated to assess efficacy and safety in inhibiting ocular pain after PRK. This research study can be added to the growing body of evidence that PRK has its unique role in the military medical setting.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.