EFCLIN 2014/ Lab Visits
By now you have probably heard that the 2014 EFCLON Congress was a great success. Attendance was up about 50% over the 2013 congress. Whether this was due to the location, promotion, or program content, we shall see. The attendee survey will shed some light on that. I was pleased to see a few IOL companies represented.
There were many good presentations including some with a little controversy. The EFCLIN board and program chair chose to continue with the Manufactures' Forum which I was happy to participate on as a panelist. I appreciate the work that goes into putting it on. The moderator Mr. Ken Payne deserves a thank you for all his efforts in organizing the event.The panel was made up of Lab people and vendors: Mr. Emmanuell Villiard of LCLS, Mr. Paul Heskett of No 7 Lab, me, Mr. Pete Chillcott of Sterling UP/Ametek, Mr. Eyal Harel of Rotlex, and Mr. Dennis Keating of Contour Diamond Tools. The Manufactures' Forum is an attempt to examine all forms of lens production; this to be covered in under 3 hours. Much of the content is applicable to IOL manufacturing. This was the agenda:
1. Two axis lathe vs three axis lathes, 2. Blocking, 3. Metrology, 4. Polish-No polish, 5. Lab Layout, 6. CE Registration, 7. Personnel Training, 8. Diamond Tooling Choices, 9. Lathe Settings, 10. Blocking Compounds, 11. Blocking Tooling Choices, 12. De-blocking Methods, 13. Edge Profiling- polish in or lathe turned.
As you can see, this was an ambitious undertaking that, without time management, could take a week.Mr. Payne led off with a discussion of the use of 3 axis (R-Theta) lathes and 2 axis (X-Z) lathes. Details such as how the diamond tool interacts with the lens surface and access for large diameter lenses were discussed. On a 3-axis lathe, the tip of the diamond tool is in constant contact with the lens material. On a 2-axis lathe, a certain amount of the tool radius is in contact with the lens material. This was clearly explained by Mr. Dennis Keating. This generated some comments from the audience about diamond life and surface quality.Since scleral lenses are becoming more common, the usefulness of the two types of lathes was discussed.
The conclusion was that the tooling on a two-axis lathe offered greater clearance to turn large diameter base curves with deep sagittal depths.Another feature that two axis lathes offer is the increased room to mount additional tools for edge profiling, fast tool servo, and milling head for IOL's.As this discussion progressed, I sensed that Mr. Payne saw it as somewhat academic, since only two axis lathes have been offered for almost two decades, now.
He moved on to the subject of blocking. Static blockers have been the industry standard for a decade or so and in the last 5 years there has been a movement to blocking the lens blank and transfer blocking for fronts. It is interesting that the IOL industry has utilized transfer blocking almost from its inception. Mr. Payne raised questions about the practice of holding the lens blank in the lathe collet rather than blocking the lens blank. This generated comments from the lab people on the panel and of course, me. As it turns out, the two lab people block the lens blank and transfer block it for the front surface. But I know that there were many lab people in the audience who hold the lens blank in the lathe collet to turn the base curve with success. So. both methods work, proven by the fit of the lens on the eye.
The takeaway is to make the best of the system you use in terms of speed, prism control, and optical quality. A new topic in this from was Metrology. Does the use of interferometers and similar hi-resolution inspection equipment really help the manufacturing process? Mr. Harel had a suggestion that this equipment helped in determining when to change a diamond tool and to identify sources of process error using statistical process control methods. I have not seen this use except in only the largest companies. It is certainly worth looking into. The question of polish or no-polish was discussed. It appears that for the majority of labs, RGP lenses need polishing, and some labs are not polishing soft lenses.One subject that was not covered was blocker calibration. I talked to a few lab people after the forum and was interested in what they had to say.
They had made a distinction between system calibration and validation. They said calibration is the physical adjustment of a component and verifying the result while validation is the confirming that component is within operational tolerances. As far as runout is concerned, they put a gage pin in the lathe collets and checked them for run-out, cleaned them if needed, blocked a few BC's and checked them for run-out. They said this validation procedure resulted in in-tolerance operation. They rarely needed to adjust the blocker.The forum proceeded on to the use of blocking compounds and their applications. I have found the use of water-soluble blocking compound on soft lenses to be an interesting subject. I know of a few labs that use it in this application, but I have also heard that it is a big no no. The jury is still out on this.