An estimated 45 million people in the US wear contact lenses.1 Contact lens fittings and sales are a main-stay of many optometric practices. Studies have shown that contact lens wearers are seen for eye exams every 14 months, while patients who solely wear glasses are seen every 28 months.
A recent survey of high-producing independent optometrists estimated contact lens sales and fittings to make up 20% of their gross revenue.2 Knowing which types of contact lenses are best for each patient's lifestyle and health needs will build your patient’s trust and save you chair time.
A 2020 literature review found that 21.7% of contact lens wearers drop out, with the most common reasons being vision issues and discomfort in new and established wearers, respectively. It was stated that up to 75% of patients who drop out of contact lenses are able to successfully return to contact lens wear if given the opportunity.
These statistics emphasize the importance of lens selection, patient education, and dry eye management.3 In terms of practice revenue, contact lens patients are very valuable.
Overview of types of contact lenses
With the multitude of contact lens modalities and technologies, it can feel overwhelming to determine which type of contact lenses to prescribe for a patient. While most patients look to contact lenses to eliminate or reduce their dependence on glasses, there are many factors to consider when determining which type of contact lens will provide the best opportunity for successful wear.
Contact lens material, lens design, replacement schedule, patient corneal status, and refraction are important considerations to enhance patient comfort, ocular health, and vision for wearers.
Download the Contact Lens Cheat Sheet here!
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Contact Lens Cheat Sheet
This cheat sheet outlines key characteristics and patient selection and fitting pearls for the many contact lens modalities available to optometrists.
Soft disposable contact lenses
Ninety percent of contact lens wearers use soft contact lenses.1 The most common disposal schedules for soft contact lenses are monthly disposable and daily disposable contact lenses. Additionally, 94% of daily disposable lens wearers are compliant to a level of 70% or higher. This number drops to 68% for wearers of monthly replacement and just 18 percent for those replacing lenses at two-week intervals.4
As of 2019, daily disposable contact lenses accounted for 38% of all contact lenses prescribed in the United States. Denmark and Finland are leading the way in daily disposable lens use, where it is reported that 71% of contact lens wearers are in daily disposables. It is widely accepted that daily disposables are the healthier option.
The rate of corneal infiltrates for daily disposable lenses is significantly lower at 0.2% per year compared to those for reusable contact lenses at 3.3 to 7.2%. Daily disposable contact lenses can significantly improve comfort and wear time, especially for patients with ocular surface dryness or allergies. Of course, the management of dry eye and eyelid hygiene is important with any contact lens modality.5
Understanding soft contact lens base curves
Soft contact lens base curves (BCs) range from 8.3 to 8.8 for standard-range lenses. Rarely do I find myself needing to change the base curve of a soft contact lens due to patient comfort or fit. However, you will have the occasional patient where the base curve of the contact lenses needs to be considered. When a contact lens is too tight or has excessive movement, looking at the K readings can be helpful in selecting a lens.
A general rule of thumb is:
- If the flat K is >45.00D, fit a steeper base curve (8.3, 8.4)
- If the flat K is between 41.00D and 45.00D, fit a median base curve (8.5 to 8.7)
- If the flat K is <41.00D, fit a flatter base curve
However, making a change to the base curve or sag depth may not be as reliable as it seems. A study of lens parameters showed that changing diameter or BC between different brands or between lens designs within the same brand may not change the fit in a predictable fashion due to variations in material, water content, and modulus.6
If the lens is well-centered, provides full coverage over the limbus, and moves an appropriate amount to allow tear film exchange for optimal corneal health, most patients will do well in the limited diameter and base curve choices of each company.
If there is a patient whose parameters lie outside those covered by a conventional soft lens, a custom soft lens can be a great alternative. Horizontal visible iris diameter (HVID) is another consideration if the patient is having difficulty. The average HVID is about 11.8mm, and a patient with a corneal size that falls outside of the 11.6mm to 12.0mm range may be a good candidate for a custom soft lens.7
Toric contact lenses
Our patients want to see as well in their contact lenses as they do in their glasses. Many commercially available soft contact lenses start with -0.75 cylinder and offer up to -2.25 cylinder. Bausch and Lomb Ultra for Astigmatism includes -2.75 cyl in their standard fitting set. For astigmatism higher than -2.75, consider an extended range toric contact lens.
The price for extended range contact lenses does increase compared to standard contact lenses, so it may be worth showing the patient what their vision looks like with a spherical equivalent of the uncorrected astigmatism in the phoropter or trial frame. For example, if a patient has a refraction of -1.00-3.75x090, you can show them what this prescription looks like compared to -1.50-2.75x090. This will give them a better understanding of why an extended range toric lens is recommended and will allow them to make an informed decision about their contact lenses.
Consider the prescription in each eye when prescribing toric contact lenses. Patients who have a mild amount of astigmatism in one eye (-1.00 or less) and negligible astigmatism in the other eye can sometimes do well with spherical lenses in both eyes. This decision is determined by the axis of astigmatism, patient personality, and visual demand while wearing contact lenses.
Considering patient personality and lifestyle in toric lens selection
For a patient with a type A personality who has against-the-rule astigmatism and wears their contact lenses every day, they will likely appreciate a difference in clarity with a toric contact lens. On the other hand, if the patient has with-the-rule astigmatism and is only using their contact lenses for weekends or sports, spherical lenses will likely provide satisfactory vision.
For these part-time contact lens wearers, it can be helpful to ask questions about why they don’t wear their contact lenses full-time. While some patients simply prefer glasses wear, this question can uncover potential reasons for future contact lens dropout, such as contact lens-related dryness or if the patient dislikes having to use reading glasses over their contact lenses.
Multifocal contact lenses
While these lenses are life-changing for presbyopic patients, they are very likely the most frustrating type of contact lenses to fit for the new practitioner. These lenses are great for patients who are tired of wearing readers over their contact lenses or who are new wearers. My advice is to pick a couple of types of soft multifocal lenses, some monthly and some daily, and become very comfortable fitting them.
It can be overwhelming quickly with all of the modifiable factors in each lens design and can use up a lot of chair time with the initial fit and follow-up exams. The fitting guides and designs are different for all multifocals, but one thing holds true among any brand—use as much plus power for the distance as the patient can tolerate for satisfactory distance vision.
This is especially true for any Alcon multifocal (Air Optix, Dailies Aqua Comfort Plus, and Dailies Total 1). I find the best success with a starting point of +0.50 over the spherical equivalent for the distance (the fitting guide recommends starting with +0.25 more plus). The vast majority of patients do well with a low or medium add power as long as you are giving the extra plus power for distance.
These lenses also do a good job of masking astigmatism. I’ve found patients with astigmatism up to -1.25 doing well in these multifocals. As we all know, fitting contact lenses on patients with presbyopia and astigmatism is a special kind of challenge. These daily multifocals have been a game changer for my patients’ success in multifocal contact lenses.
Patient education around vision expectations with multifocal lenses
Patient education and setting expectations are crucial for success with new multifocal contact lens wearers. A discussion before the initial fit that these lenses are great for most things most of the time but that the vision will likely not be as clear as it is with their glasses. These lenses will allow the patient good functional vision at distance and near, and the goal is to find a balance in prescription that works for both.
Night-time driving and difficulty with glare can be side effects of multifocal contact lenses. Pupil size plays a role in visual outcomes in soft and rigid gas permeable (RGP) multifocal lenses. In order for the multifocal lens to sufficiently achieve satisfactory distance and near vision in most soft designs, the pupil should ideally be between 3mm to 5mm. If the pupil is greater than 5mm, patients may experience glare.8
If the patient’s vision is not sufficient with a simultaneous vision design, a translating gas permeable (GP) multifocal or a specialty lens with a modifiable multifocal zone size may be a better fit.
Extended wear contact lenses
It is uncommon for optometrists to recommend overnight wear of contact lenses (other than approved ortho-k lenses). However, it is important to be familiar with the extended wear contact lens options on the market. These are lenses that are FDA-approved for the patient to keep in the eyes without removal for a given length of time.
There may be some instances that these lenses are helpful or even necessary based on the patient’s profession, such as firefighters or on-call medication professionals. Encourage frequent removal and cleaning, glasses wear when possible to allow more oxygen to the cornea, and educate patients that sleeping in contact lenses of any kind increases the risk for eye infections.
Scleral contact lenses
These contact lenses have many indications revolving around corneal disease. In patients with irregular corneas, such as those with keratoconus or refractive surgery complications, the tear reservoir of the lens works to mimic a smooth cornea, restoring vision. Another primary purpose for scleral lenses is to allow for corneal healing and protection by creating an environment of preservative-free artificial tears, plasma tears, or other medications as needed.
There are various fitting methods for these lenses, ranging from using fit sets in the office (empirical fitting) to using K’s, Rx, and HVID to calculate an initial lab-made lens (diagnostic fitting) to corneal molding. Regardless of the fitting method, a careful assessment of the lenses is important to ensure no impingement or blanching of vessels is noted.
These lenses tend to require more follow-ups and be more labor-intensive for patients as they require sterile saline and often DMVs/plungers for insertion and removal. When deciding between a scleral lens and a corneal RGP lens, there are many factors to consider, such as patient dexterity, dry eyes, corneal status, and corneal topography.
Topographically, scleral lenses are recommended when the difference between the highest and lowest point along the meridian with the greatest difference is less than 350µm. However, this may no longer be a limiting factor as advancements in corneal mapping software allow for lens designs to mirror a patient’s unique corneal topography.9
Rigid gas permeable contact lenses
As of 2021, only 10% of contact lens wearers use rigid gas permeable contact lenses.10 While soft contact lenses have replaced RGPs as the contact lens of choice for most patients, there are cases when RGPs will provide superior vision and should be considered.
This is especially the case when moderate to high astigmatism is involved. RGPs can also be considered for presbyopic patients who struggle to achieve satisfactory vision with soft multifocal or monovision contact lenses. Initial discomfort is one of the main obstacles with RGPs, so patient education is crucial. Consider using a topical anesthetic drop when first inserting the contact lenses to gradually allow the patient to get used to the sensation of the lens.
This is especially helpful for patients who are nervous about initial lens insertion. A gradual increase in wear time is also helpful for patients who have difficulty adapting to RGPs. Detailing a wear schedule with increased wear time between initial fit and follow-up is a good way to determine if the patient is adapting to the lenses.
Fitting lenses using a topography-based software can also help with initial adaptation as these lenses are custom designed to fit the patient’s cornea. Diameter is another factor to consider, as larger diameter lenses (14.3mm and up) have been shown to improve comfort over smaller diameter lenses.
Hybrid contact lenses
These lenses consist of a rigid gas permeable lens surrounded by a soft lens skirt. The idea behind the lenses is that they provide the clarity of an RGP without the initial discomfort and adaptation period associated with RGPs. These lenses are useful for correcting corneal astigmatism, as you would expect from an RGP.
Good candidates for these lenses include patients who are experiencing vision fluctuation or lens rotation in toric soft lenses, who are presbyopic and not satisfied with the vision in soft multifocal lenses, patients interested in RGPs but concerned about the comfort, and patients with irregular corneas looking to try other options.
These lenses do come with a higher price tag than soft or RGP lenses, so be sure to discuss the benefits of these lenses and why you are recommending this lens modality.
Ortho-k/Corneal refractive therapy contact lenses
It’s not hard to notice the recent industry focus on myopia management. Ortho-k lenses play a role in myopia control for children but can also be excellent for adults. Often, patients will be interested in laser in situ keratomileusis (LASIK) but concerned about the potential side effects or costs. Ortho-k lenses offer a way for these patients to be glasses and contact lenses free during the day without surgical correction.
The ideal refraction for ortho-k correction is -6.00 and under with minimal astigmatism. Depending on your comfort and the fitting modality you use, it is possible to fit a wide range of patients with higher prescriptions. Wave custom contact lenses system is the software that I use to design ortho-k lenses. It enables me to use the patient’s topography to design the fit of the lens.
This allows for greater comfort in the lenses and fewer adjustments needed compared to other fitting methods, most notably for those patients who do not fit the ideal prescription range, such as patients with hyperopia, high myopia, and astigmatism.
Color prosthetic contact lenses
There are many potential indications for colored contact lenses outside of cosmetic eye color enhancement. Color contact lenses can be used to therapeutically alter vision or mask ocular irregularities. Transparent tinted contact lenses can be used to enhance vision, especially for sports or outdoor activities.
Gray-green tinted lenses are made for open-air sports and recreational activities on land or water. Amber-tinted lenses are better for dynamic sports and enhancing contrast. Altius contact lens manufacturer has daily tinted contact lenses available in packs of 10, 30, and 90 lenses in plano or with the patient's prescription.
For patients with corneal scarring, iris irregularities, photophobia, or other conditions, custom-colored contact lenses can be life-altering. Iris defects, such as traumatic mydriasis or halos post-iridectomy, often cause photophobia and glare. A colored iris lens with a clear pupil can improve visual symptoms and cosmetic symmetry.
For albino patients whose lack of pigmentation causes extreme photosensitivity, darker-colored contact lenses can act as filters. Compared with sunglasses, contact lenses provide complete pupillary coverage and limit peripheral glare.
The diameter of the colored iris should be 2mm to 3mm larger than the patient’s pupil in dim illumination.11 In some cases, such as Coats disease or leukocoria, the patient may have one white pupil. For non-seeing eyes, a black pupil with a matching opaque iris can improve a patient’s cosmesis and self-esteem.
As eyecare professionals, we emphasize the treatment of underlying ocular pathology and the management of ocular health, but we must not neglect the emotional aspect that comes with patients who have visible ocular conditions or irregularities.
Key takeaway
Every contact lens wearer needs to be managed as an individual. Assess their visual needs, motivation for contact lens wear, ocular and systemic health, and refractive and corneal parameters.
Completing a thorough history and ocular assessment and prescribing a specific contact lens for their individual needs can set the patient up for success.
